Question

sabendo que sen 74°=24/25 qual o valor do cos 74°​

Answer 1

Sin^2(74)+cos^2(74)=1
(24/25)^2 +cos^2(74)=1
cos^2(74)=1-(576/625)
cos^2(74)=(625-576)/625
cos^2(74)=(49/625)
cos(74)=7/25

Answer 2

$( \frac{24}{25} ) {}^{2} + \cos {}^{2} (74) = 1 \\ \\ \frac{576}{625} + cos {}^{2} (74) = 1 \\ \\ cos {}^{2} (74) = \frac{625}{625} - \frac{576}{625} \\ \\ cos {}^{2} (74) = \frac{49}{625} \\ \\ \sqrt{cos {}^{2} } (74) = ± \sqrt{ \frac{49}{625} } \\ \\ cos(74) = ± \frac{7}{25}$

Fique com o valor positivo.