If sin 3A=cos(A−10o) and 3A is acute then, find ∠ A .
Given: sin 3A=cos(A−10o) sin 3A=cos(90o−3A)....(∵sin θ=cos(90o−θ))
cos(90o−3A)=cos(A−10)⇒90o−3A=A−10o⇒100o=4A∴A=25o