Given that the terminal edge of angle a passes through point m (7, - 24), then Sina + cosa = -————
X = 7, y = ~ 24 get r = 25, so Sina = ~ 24 / 25, cosa = 7 / 25 get Sina + cosa = ~ 17 / 25
Given Sina = 2m-3, what is the range of M?
-1≤sina≤1
So - 1 ≤ 2m - 3 ≤ 1
2≤2m≤4
1≤m≤2
Given that sina / 2 = 3 / 5, cosx / 2 = - 4 / 5, try to determine the quadrant of angle A
sina=2*sina/2*cosa/2=-24/25,
cosa=(cosa/2)*(cosa/2)-(sina/2)*(sina/2)=7/25,
Because sina is negative and cosa is positive, angle a is in the second quadrant
If x is the third quadrant angle and cosx / 2 < 0, then which quadrant is x / 2? I want to judge Sina
If x is the third quadrant angle, and cosx / 2 < 0, then which quadrant is x / 2? I want to judge whether sina is positive or negative, then in the second quadrant, the hypotenuse is positive or negative?
X / 2 is the second quadrant, because x is the third quadrant, so pi / 2