Where sin θ = opphyp\frac{\text{opp}}{\text{hyp}}hypopp → −35\frac{-3}{5}5−3
opp = -3, hyp = 5
using pythagoras formula
hyp2^{2}2 = adj2^{2}2 + opp2^{2}2
adj2^{2}2 = hyp2^{2}2 - opp2^{2}2
adj2^{2}2 = 52^{2}2 - 32^{2}2 → 25 - 9
adj2^{2}2 = 16
adj = 4
cos θ = adjhyp\frac{\text{adj}}{\text{hyp}}hypadj → 45\frac{4}{5}54
In third quadrant: cos θ is negative → - 45\frac{4}{5}54
