JAMB - Mathematics (2005 - No. 27)
If sin θ = -1/2 for 0 < θ < 360o, the value of θ is
30o and 150o
150o and 210o
210o and 330o
150o and 330o
คำอธิบาย
sin θ = -1/2
= -0.5
θ = sin-1 (0.5)
θ = 30o
Since θ is negative
θ = 180 + 30 = 210o
θ = 360 - 30 = 330o
∴θ = 210o and 330o
= -0.5
θ = sin-1 (0.5)
θ = 30o
Since θ is negative
θ = 180 + 30 = 210o
θ = 360 - 30 = 330o
∴θ = 210o and 330o