Question

if theta +fi =60 degree show that sin (120-theta)=cos(30-fi)​

Answer 1

Answer:

θ+ϕ=αtanθ=tanα

tanϕ

tanθ

=

1

k

Applying componendo and dividendo

tanθ+tanϕ

tanθ−tanϕ

=

k+1

k−1

cosθ

sinθ

+

cosϕ

sinϕ

cosθ

sinθ

−

cosϕ

sinϕ

=

k+1

k−1

sin(θ+ϕ)

sin(θ−ϕ)

=

k+1

k−1

sinα

sin(θ−ϕ)

=

k+1

k−1

sin(θ−ϕ)=(

k+1

k−1

)sinα