Question

已知sinα-cosα=1/5,则sinαcosα的值为?

Answer 1

sinα-cosα=1/5,则

(sinα-cosα)^2=1/25

(sinα)^2+(cosα)^2-2sinαcosα=1-2sinαcosα = 1/25

2sinαcosα = 24/25

sinαcosα=12/25