已知cos(π/2+α)=2sin(α-π/2),求[sin^3(π+α)+cos(α+π)]/[5cos(5π/2-α)+3sin(7π/2-α)]=

问题描述:

已知cos(π/2+α)=2sin(α-π/2),求[sin^3(π+α)+cos(α+π)]/[5cos(5π/2-α)+3sin(7π/2-α)]=