Given tan theta=-8/5 and sin theta < 0, find cos theta.

Answer 1

if tanØ < 0 and sinØ < 0 , then Ø must be in quad IV
from tanØ = -8/5 in IV, we have x = 5, y = -8
r^2 = 25+64 = 89
r = √89

then cosØ = 5/√89

Answer 2

Nahi samjha