Question

Ajudinha please D:
Sabendo que senθ = 4/5, qual é o valor de cosθ?

Answer 1

sen^2 (a) + cos^2 (a) = 1
(4/5)^2 + cos^2 (a) = 1
16/25 + cos^2 (a) = 1
cos^2 (a) = 1 - 16/25
cos^2 (a) = 9/25
cos(a) = √(9/25)
cos(a) = 3/5