Question

Suppose that cos(t) = 5/13, where t is the fourth quadrant. find sin(2t)

Answer 1

Given that cos(t)= 5/13

t is in fourth quadrant, so sint<0 and cost>0

So sint = -sqrt(1-cos^2(t))= -sqrt(1-25/169)= - sqrt((169-25)/169)= -12/13

Sin(2t) = 2sin(t)cos(t)= 2*-12/13* 5/13 = -120/169