What is sin(arccos(5/13))sin(arccos(513))?

1 Answer
Jul 21, 2015

12/131213

Explanation:

First consider that : theta=arccos(5/13)θ=arccos(513)

thetaθ just represents an angle.

This means that we are looking for color(red)sin(theta)!sin(θ)!

If theta=arccos(5/13)θ=arccos(513) then,

=>cos(theta)=5/13cos(θ)=513

To find sin(theta)sin(θ) We use the identity : sin^2(theta)=1-cos^2(theta)sin2(θ)=1cos2(θ)

=>sin(theta)=sqrt(1-cos^2(theta)sin(θ)=1cos2(θ)

=>sin(theta)=sqrt(1-(5/13)^2)=sqrt((169-25)/169)=sqrt(144/169)=color(blue)(12/13)sin(θ)=1(513)2=16925169=144169=1213