WAEC - Mathematics (1998 - No. 4)
Cos x is negative and sin x is negative.Which of the following is true of x?
0o < x < 90o
90o < x <180o
180o < x < 270o
270o < x <360o
-90o < x <90o
Explicación
In the 3rd quadrant, only the tan of angles are positive.
The 3rd quadrant = 180° < x < 270°