Question

Calculati valoarea expresiei sin patrat 20^+sin patrat 70^.

Answer 1

$\it sin70^o=cos(90^o-70^o)=cos20^o \Rightarrow sin^2 70^o=cos^2 20^o\ \ \ \ (*)\\ \\ sin^220^o+sin^2 70^o\ \stackrel{(*)}{=}\ sin^2 20^o+cos^2 20^o=1$

Answer 2

Răspuns:

1

Explicație:

sin patrat 20^+sin patrat 70^ =

cos^2 (90-20) + sin^2 70 =

cos^2 70 + sin^2 70 =

1.