Identitas trigonometri 1- sin⁴ x=cos² x (1+sin² x) ​

Jawaban:

buktikan dg ruas kanan

= 1 – sin⁴x

= ( 1 – sin²x ) ( 1 + sin²x )

= cos²x ( 1 + sin²x )

atau buktikan dg ruas kiri

= cos²x ( 1 + sin²x )

= cos²x + cos²x sin²x

= ( 1 – sin²x ) + ( 1 – sin²x ) sin²x

= 1 – sin²x + sin²x – sin⁴x

= 1 – sin⁴x