Find the value of .
Suppose is a right-angled triangle. If , , and , then the ratio of the lengths of the
triangle's sides is as follows:
The tangent of an angle in a right-angled triangle is equal to the
ratio of the length of the opposite side to the length of the
adjacent side. The triangle shows that and that . The cosine of
an angle is equal to the ratio of the length of the adjacent side
to the length of the hypotenuse. The triangle shows that . Use
this knowledge to find the value of the expression .
Thus, the value of the expression is .