Find (a) sin 2t, (b) cos 2t, (c) tan 2t, and (d) the quadrant containing 2t.

Question

cos t = −5/13, 1/2π < t < π

Answer 1

isn't cos(2t)<0, ie isn't (-5/13)²-(12/13)²<0, therefore the ambiguity is resolved and 2t is in Q3

and sin(2t)=2*(12/13)*(-5/13)

Answer 2

Draw and label a diagram!

cos t = -5 / 13, sin t = ?, tan t = ?

Use the appropriate formula and answer.