Question

4sin^a-3sinacosa-5cos^a 怎么计算 知道tana=2

Answer 1

同除以然后直接用求根公式.

cos^A,4sin^a-3sinacosa-5cos^a

=(4sin^a-3sinacosa-5cos^a)/sin^a+cos^a

=4tan^a-3tana-5=4*4-3*2-5=5