Angle θ lies in the second quadrant, and sin θ = 3/5. Find cos θ and tan θ.

Question

Angle θ lies in the second quadrant, and sin θ = 3/5.
Find cos θ and tan θ.

Steve · Accepted Answer

Draw the triangle.

sinθ = y/r
cosθ = x/r
tanθ = y/x

In QII,
y = 3
x = -4
r = 5

so,

cosθ = -4/5
tanθ = -3/4

Angle θ lies in the second quadrant, and sin θ = 3/5.