Right Angle: A right angle is an angle that measures exactly 90 degrees, or one-quarter of a complete circle.
Pythagorean Theorem:The Pythagorean Theorem states that in a right-angled 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.
Trigonometric Ratios: The trigonometric ratios, such as sine, cosine, and tangent, are defined using the lengths of the sides of a right-angled triangle, with the hypotenuse being a key component.