Vector a = (sin θ, 2), vector b = (COS θ, 1), vector a parallel, vector B, θ belong to (0, π / 2), (1) find Tan θ (2) Find sin θ and cos θ; (3) If sin (θ - φ) = 3 / 5,0

Vector a = (sin θ, 2), vector b = (COS θ, 1), vector a parallel, vector B, θ belong to (0, π / 2), (1) find Tan θ (2) Find sin θ and cos θ; (3) If sin (θ - φ) = 3 / 5,0

Vector a parallel vector b ------ > x1y2 = x2y1
∴sinθ=2cosθ
tanθ=2
(2)
sinθ=2cosθ
θ belongs to (0, π / 2)
∴sinθ=2cosθ>0
∵sin²θ+cos²θ=1
∴sinθ=2√5/5
cosθ=√5/5
(3)
0