Question

If cos theta is -5/13 and sin θ < 0, what is tan θ ?

Answer 1

take the right angled triangle with sides 13, 12 and 5. sine theta will be 12/13

When sin theta < 0 and cos theta < 0 we are in the third quadrant so sin theta will be -12/13

tan theta = sin theta / cos theta = -5/13 / -12/13 = -5*13 / -12*13 = 5/12