Question

Find sin 20(this is theta not 0) if 0(theta) is in the first
quadrant and tan 0(theta) = 40/9

Answer 1

Explanation:

Using the Identity, sin2θ=2tanθ1+tan2θ, we get,

sin2θ=2⋅4091+(409)2,

=809÷168181.

⇒sin2θ=7201681.

θ∈Q1⇒0<θ<π2⇒0<2θ<π.

∴sin2θ>0.