2.3 Applications of Right Triangle Trigonometry

2 min readjuly 25, 2024

Right triangle trigonometry isn't just math—it's a tool for solving real-world problems. From figuring out building heights to designing ramps, it helps us make sense of shapes and angles in everyday life.

We'll look at how to spot right triangles in real situations, tackle elevation problems, and use trig ratios for measurements. Plus, we'll see how these skills apply in science, engineering, and navigation.

Applications of Right Triangle Trigonometry

Modeling with right triangle trigonometry

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  • Identify right triangles in real-world scenarios buildings and shadows form right triangles, ladders against walls create right triangles, ramps and inclines involve right triangles
  • Recognize known and unknown elements in the situation given information might include lengths or angles, required information determines solution approach
  • Translate real-world problem into mathematical model by drawing diagram representing situation, labeling known sides and angles, identifying needed trigonometric ratios

Problems with elevation angles

  • Understand angles of elevation and depression formed above or below horizontal line of sight
  • Identify observer's position and object of interest crucial for problem setup
  • Draw and label diagrams for elevation and depression problems include horizontal line of sight, mark angle of elevation or depression
  • Apply appropriate trigonometric ratios to solve for unknown values use for distances, or when appropriate based on given information

Trigonometric ratios for measurements

  • Apply sine ratio to find unknown heights sin(θ)=opposite[hypotenuse](https://www.fiveableKeyTerm:hypotenuse)\sin(\theta) = \frac{\text{opposite}}{\text{[hypotenuse](https://www.fiveableKeyTerm:hypotenuse)}} useful for tall structures (buildings, trees)
  • Use cosine ratio to calculate unknown distances cos(θ)=adjacenthypotenuse\cos(\theta) = \frac{\text{adjacent}}{\text{hypotenuse}} helpful in surveying and navigation
  • Employ tangent ratio for slope-related problems tan(θ)=oppositeadjacent\tan(\theta) = \frac{\text{opposite}}{\text{adjacent}} applicable to ramp designs, roof pitches
  • Solve multi-step problems involving combinations of ratios complex scenarios may require multiple trigonometric functions
  • Account for real-world considerations factor in eye level of observer, instrument in surveying for accurate measurements

Applications in science and engineering

  • Physics applications calculate vector components, determine resultant forces, analyze projectile motion trajectories
  • Engineering applications compute truss forces in bridges, design wheelchair ramps, calculate cable tensions in suspension bridges
  • Navigation applications determine distances on maps, calculate headings for ships, estimate positions using triangulation methods
  • Surveying and construction measure land elevations for site planning, calculate building heights for zoning compliance, estimate roofing material needs

Key Terms to Review (17)

30-60-90 triangle: A 30-60-90 triangle is a special type of right triangle where the angles measure 30 degrees, 60 degrees, and 90 degrees. This triangle has a consistent ratio between its sides, making it particularly useful in various mathematical applications. Understanding the properties of this triangle helps in simplifying calculations involving trigonometric functions and geometric problems, leading to efficient problem-solving strategies.
45-45-90 triangle: A 45-45-90 triangle is a special type of right triangle where the two non-hypotenuse angles are each 45 degrees. This unique triangle has side lengths that follow a specific ratio: the lengths of the legs are equal, and the length of the hypotenuse is equal to the length of a leg multiplied by the square root of 2. Understanding this triangle helps in solving problems related to right triangle trigonometry, making it easier to determine unknown side lengths and angles in various applications.
Adjacent side: The adjacent side in a right triangle is the side that forms one of the angles of interest, specifically the angle that is not the right angle. It is important because it helps define the trigonometric ratios, such as cosine and tangent, which relate the lengths of the sides of a triangle to its angles. Understanding this term is crucial for solving triangles and applying trigonometric concepts effectively.
Cosine: Cosine is a fundamental trigonometric function that relates the angle of a right triangle to the ratio of the length of the adjacent side to the length of the hypotenuse. This relationship holds true in various contexts, from defining circular functions on the unit circle to solving complex triangles, making it essential in understanding angles and their measures.
Distance: In mathematics, distance refers to the numerical measurement of space between two points. It plays a critical role in right triangle trigonometry, where the distance between points can be calculated using various methods such as the Pythagorean theorem and trigonometric ratios. Understanding distance is essential for solving problems related to angles, sides of triangles, and real-world applications like navigation and construction.
GPS: GPS, or Global Positioning System, is a satellite-based navigation system that allows a GPS receiver to determine its exact location (latitude, longitude, and altitude) anywhere on Earth. This technology uses signals from a network of satellites to provide accurate positioning and timing information, making it a valuable tool for various applications, including navigation, mapping, and surveying.
Height: Height, in the context of right triangle trigonometry, refers to the perpendicular distance from the base of a triangle to its opposite vertex. This concept is essential for understanding how to apply trigonometric ratios and formulas to solve real-world problems involving triangles, especially when determining distances that are not directly measurable. Knowing the height allows for the calculation of area and serves as a vital component in various applications such as physics, engineering, and architecture.
Hypotenuse: The hypotenuse is the longest side of a right triangle, opposite the right angle. This side is crucial in trigonometry as it serves as a reference point for defining the other sides in relation to angles, and is essential for applying various trigonometric functions and identities. Understanding the hypotenuse is vital for solving right triangles and analyzing problems involving angles and distances.
Inverse trigonometric functions: Inverse trigonometric functions are functions that allow us to determine the angle associated with a given trigonometric ratio. They are the inverses of the basic trigonometric functions such as sine, cosine, and tangent, meaning that they take a value from the range of these functions and return the corresponding angle. Understanding inverse trigonometric functions is essential for solving various problems related to right triangle trigonometry and for manipulating basic trigonometric equations.
Law of Cosines: The Law of Cosines is a mathematical formula used to find a side or angle in any triangle when certain other sides or angles are known. This law extends the Pythagorean theorem, allowing calculations for non-right triangles by relating the lengths of the sides of the triangle to the cosine of one of its angles. It is particularly useful in situations where two sides and the included angle, or all three sides, are known.
Opposite side: The opposite side in a triangle is the side that is directly across from a specific angle, playing a crucial role in trigonometric calculations. This term is essential for understanding relationships between angles and sides in right triangles and is also significant in solving more complex triangles, as it helps define ratios in trigonometric functions like sine, cosine, and tangent.
Pythagorean Theorem: The Pythagorean Theorem states that in a right triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the lengths of the other two sides. This fundamental relationship is crucial in trigonometry, as it helps establish connections between angles and side lengths in right triangles. It serves as a basis for solving various problems involving right triangles, enabling applications in real-world scenarios and forming the foundation for concepts in physics and engineering.
Shadow length: Shadow length refers to the distance from the base of an object to the tip of its shadow on the ground, which is influenced by the angle of the light source, typically the sun. Understanding shadow length is important for various applications, such as determining the height of objects, calculating angles of elevation and depression, and solving real-world problems using right triangle trigonometry.
Sine: Sine is a fundamental trigonometric function that relates the angle of a right triangle to the ratio of the length of the opposite side to the length of the hypotenuse. This relationship extends beyond right triangles to various contexts, such as the unit circle and periodic functions, where sine represents the y-coordinate of a point on the unit circle corresponding to a given angle.
Sohcahtoa: Sohcahtoa is a mnemonic that helps remember the relationships between the angles and sides of a right triangle. It stands for 'Sine = Opposite over Hypotenuse', 'Cosine = Adjacent over Hypotenuse', and 'Tangent = Opposite over Adjacent'. This simple phrase captures the core concepts needed to solve problems involving right triangle trigonometry and is essential for understanding various applications in real-world scenarios, such as physics, engineering, and architecture.
Tangent: The tangent function, often abbreviated as 'tan', relates the angle of a right triangle to the ratio of the length of the opposite side to the length of the adjacent side. This function is crucial in various branches of mathematics, especially in solving triangles and modeling periodic phenomena.
Theodolite: A theodolite is a precision instrument used for measuring angles in the horizontal and vertical planes. It is widely utilized in surveying and engineering to determine land boundaries, create maps, and establish construction sites. The theodolite’s ability to provide accurate angular measurements makes it a vital tool in applications that rely on right triangle trigonometry for distance and height calculations.
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