Sides Of A Right Triangle

Hypotenuse, Adjacent and Opposite Sides.

In the following right triangle PQR,

• the side PQ, which is opposite to the right angle PRQ is called the hypotenuse. The hypotenuse is the longest side of the right triangle.
• the side RQ is called the adjacent side of angle θ.
• the side PR is called the opposite side of angle θ.

Note: The adjacent and the opposite sides depend on the angle θ. For complementary angle of θ, the labels of the 2 sides are reversed.

Example:
Identify the hypotenuse, adjacent side and opposite side in the following triangle:
a) for angle x
b) for angle y

Solution:
a) For angle x: AB is the hypotenuse, AC is the adjacent side , and BC is the opposite side.
b) For angle y: AB is the hypotenuse, BC is the adjacent side , and AC is the opposite side.