The Pythagorean Theorem,
a
2
+
b
2
=
c
2
,
a
2
+
b
2
=
c
2
,
can be used to find the length of any side of a right triangle. right angle has a value of 90 degrees (
90
∘
90
∘
). A right triangle is a triangle in which one angle is a right angle. The relation between the sides and angles of a right triangle is the basis for trigonometry.
The side opposite the right angle is called the hypotenuse (side
c
c
in the figure). The sides adjacent to the right angle are called legs (sides
a
a
and
b
b
). Side
a
a
may be identified as the side adjacent to angle
B
B
and opposed to (or opposite) angle
A
A
. Side
b
b
is the side adjacent to angle
A
A
and opposed to angle
B
B
.
The hypotenuse c, opposite the right angle, is the longest side. The legs are shorter and may be the same or different lengths, and are perpendicular to each other in a right triangle.