Thread: find the angle with the greek letter

in the triangle ABC, AC=3, BC=2, angleBAC=theta and angleABC=2theta
calculate the value of theta to the nearest tenth of a degree.
i think i'm complicating this thing for myself because i cant get farther than 2 x sin2theta = 3 x sintheta

Hello the kopite

Originally Posted by the kopite

in the triangle ABC, AC=3, BC=2, angleBAC=theta and angleABC=2theta
calculate the value of theta to the nearest tenth of a degree.
i think i'm complicating this thing for myself because i cant get farther than 2 x sin2theta = 3 x sintheta

OK, so now carry on:





or



Grandad

thanks a lot, but im here to understand. why does 2sin2theta equal 4sintheta x costheta in the first line of your reasoning?

I think its the 'Double Angle Identity' in Trigonometry.

Note that



I hope this helps.