Question

prove that sin54-sin18=1/2

Answer 1

0.80902-0.30902=0.5 or 1/2

Answer 2

or should i say 0.5=1/2

Answer 3

@GoldRush18 u have to prove it using trigonometric functions and rules , not using calculator :D

Answer 4

oh ok

Answer 5

Use cofunction identity.

Answer 6

well i got cos36-sin18 and dont know what to do , can u prove it with explanation pls :)

Answer 7

Idk if this helps, but
Sin(3theta)=3Sin(theta)-4(Sin(theta))^3

I tried using it and I got - 4 sin³ 18 + 2 sin 18 - 1/2 = 0

Answer 8

Use this identity:
\[\sin A-\sin B=2 \cos{\frac{A+B}{2}}\sin{\frac{A-B}{2}}\]

Answer 9

thanks will do that :D @blockcolder

Answer 10

thanks i got it now it should be like this
2cos(36)sin(18) and multiply by cos18/cos18 as it equals 1
so cos(36)sin(36)/cos(18) and then multiply by 2 and 1/2
so 1/2sin72/cos18 then use co function so sin72= cos18
1/2cos(18)/cos(18) cosines cancel each other so = 1/2

Answer 11

Good job! :)