Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 3 - No. 42)
Which of the following is a correct statement concerning trigonometric functions and obtuse angles?
The cosine function is positive in obtuse angles
The sine function is negative in obtuse angles.
The sine function is positive in obtuse angles.
The tangent function is positive in obtuse angles.
Giải thích
Sine function is positive for obtuse angles (quadrant II).