Question

已知f(x)=asin2x+bcos2x的值为根号7,且f(π/12)=5/2.

Answer 1

f(π/12)=asin(2*π/12)+bcos(2*π/12)=asinπ/6+bcos π/6=(5/2)

即a+√3b=5

又因为a^2+b^2=7

a=2,b=√3