Explanation:
In this right triangle:
Observe the following facts about the right triangle above:
AB is the hypotenuse, which is across
the triangle from the right angle.
BC, the side opposite angle A, is the
side that is across the triangle from angle A.
AC, the side opposite angle B is the
side that is across the triangle from angle B.
BC, the side opposite angle A is
the same side that is adjacent angle B.
AC, the side adjacent angle A is
the same side that is opposite angle B.
The definitions of the trigonometric ratios are
as follows:
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Edwin