Question

tanx=3 求3分之2sin平方加4分之一cos平方X的值

Answer 1

tanx=sinx/cosx=3

sinx=3cosx

sin^2x+cos^2x=1

9cos^2x+cos^2x=1

cos^2x=1/10

2/3(sin^2x)+(cos^2x)/4

=2/3*9cos^2x+(cos^2x)/4

=25/4 cos^2x

=25/4*1/10

=5/8