Question

已知sina=根号2cosB,tana=根号3cotB,-兀/2

Answer 1

sinA = tanA cosA = tanA √(1 - (sinA)^2)

√2 cosB = √3cotB √(1 - 2(cosB)^2)

√2 sinB = √3√(1 - 2(cosB)^2)

2(1 - (cosB)^2) = 3 - 6(cosB)^2

cosB = 1/2

B = π/3

sinA = √2/2

A = π/4