若tanα=3,则(sin^3α+2cos^3α)/(sin^3α-2cos^3α)
问题描述:
若tanα=3,则(sin^3α+2cos^3α)/(sin^3α-2cos^3α)
答
(sin^3α+2cos^3α)/(sin^3α-2cos^3α)
=(sin^3α/cos^3α+2)/(sin^3α/cos^3α-2)
=(tan^3α+2)/(tan^3α-2)
=(3^3+2)/(3^3-2)
=29/25