Question

If Sin B=Cos (2B-30) where 2B is an acute angle then the value of B=___________..please give me answer with explanations

Answer 1

I think the value of B should be 30 degree

Answer 2

sin B = cos(2B-30)       given-1
we know that
sinB=cos(90-B)                       by property -2
 Equating 1 and 2 
cos(2B-30)=cos(90-B)
therefore
2B-30=90-B
3B=120
B=120/3=40

Also 2B is given to be acute angle which will be 80.