Question

Find cos if tan = -4/3 and sin < 0

Answer 1

THe first thing we need to do is find the hypotenuse.  From the tangent we know that the legs of the right triangle are 3 and 4.  So this 2/3 of a special right triangle (3-4-5).  Thus the hypotenuse is 5.  The sin is defined as $\frac{opposite}{hypotenuse}$.  We know the opposite is 4 and hypotenuse is 5.  Thus the sin is $- \frac{4}{5}$