Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 2 - No. 29)
If sin θ = x in a right triangle, then sin(180° − θ) equals:
-x
x
1/x
0
คำอธิบาย
In the second quadrant (180 - θ), sine is positive, thus sin(180° − θ) = sin θ = x.