Question

[Kimian Hajan Ruventaren]

Mọi người giúp mk vs ạ

Answer 1

[Hồng Phúc]

13.

\(\dfrac{sinx-sin3x+sin5x}{cosx-cos3x+cos5x}\)

\(=\dfrac{2sin3x.cos2x-sin3x}{2cos3x.cos2x-cos3x}\)

\(=\dfrac{\left(2cos2x-1\right)sin3x}{\left(2cos2x-1\right)cos3x}\)

\(=\dfrac{sin3x}{cos3x}=tan3x\)

Answer 2

[Kimian Hajan Ruventaren]