Question

how to find sin 100 degree​

Answer 1

Sin(A+B)= Sin A×CosB+ SinB×CosA

Sin(100°)=Sin(90°+10°)

Sin(90°+10°)=Sin90°×Cos10°+Cos90°×Sin10°

Sin90°=1 , Cos90°=0

Sin(90°+10°)= Cos10°

Cos 3A= 4cos^(3) A- 3cos A

Cos30=√(3)/2

Let's take cos10=x

4x^3–3x-√3/2=0

Solve this cubic equation roots of this will be answer for x then check it for cosA it is possible or not

Answer 2

Answer:

sin 100 degrees can be found by

sin(90+10)= cos 10 degrees.

which is equal to 0.984.

hope it helps