What quadrant is the acute angle Are all the angles of the first quadrant acute? Are the angles less than 90 ° acute? Must the angle of the second quadrant be larger than that of the first quadrant?

What quadrant is the acute angle Are all the angles of the first quadrant acute? Are the angles less than 90 ° acute? Must the angle of the second quadrant be larger than that of the first quadrant?

Are all the corners of the first quadrant acute? No
Is an angle less than 90 ° acute? No
Must the angle of the second quadrant be larger than that of the first quadrant
Acute angle is the angle of the first quadrant!

In △ ABC, find the acute angle a suitable for the equation √ 3tan? A-4tana + √ 3 = 0

√3tan²A-4tanA+√3=0
（√3tanA-1）（tanA-√3）=0
Tan3 = / tan3 √
So a = 30 ° or 60 ° because only acute angle is required

It is known that: A and B are acute angles, then the range of a + B angle is ---? The range of A-B angle is ---?

A + B ranges from 0 degrees to 180 degrees, but not including 0 degrees and 180 degrees

If the image of the first order function y = (2a-1) x + (A-1) passes through the positive half axis of Y axis and the negative half axis of X axis, then the value range of a is () A. a＞1 Two B. a＞1 C. 1 2＜a＜1 D. a＜1 Two

According to the meaning of the question, the first order function image passes through the first, second and third quadrants,
So 2a-1 > 0 and A-1 > 0,
A > 1
Therefore, C

It is known that: θ is the third quadrant angle. If SIN3 θ ≤ 0, try to determine the final edge position of 3 θ

If θ is the third quadrant angle, then 2K π + π < θ < 2K π + 3 π / 2
6kπ+3π＜3θ＜6kπ+9π/2
That is, 3 (2k + 1) π < 3 θ < 3 (2k π) + 3 * 3 π / 2
, --- > 3 θ is the first, third and fourth quadrant angle (including + X, - Y axis)
Because SIN3 θ ≤ 0, - π / 6 "θ" 0
Conclusion: 3 θ is the fourth quadrant angle (including + X, - Y axis)

Given the point Q (m ^ 2 + 4, m ^ 2 + 6 + m), find the value of m on the bisector of the first and third quadrants And write the coordinates of Q about the symmetric point P of Y axis

m²+4=m²+6+m
m=-2
Coordinates of point Q (8,8)
Coordinates of point P (- 8,8)

Given that α is the second quadrant angle and | α + 2 | ≤ 4, then the value range of α is______ .

∵|α+2|≤4，
∴-4≤α+2≤4，
∴-6≤α≤2．
And ∵ α is the second quadrant angle,
∴-3π
2 ＜ α - π or π
2＜α≤2．
So the answer is: (- 3 π)
2，-π）∪（π
2，2]．

Given that θ is the third quadrant angle and cos θ / 2 < 0, what quadrant is θ / 2?

Because theta is the angle of the third quadrant
sinθ0
So theta / 2 is the angle of the second quadrant
Unit circle method 2K π + π

If cos (75 ° + α) = 1 / 3 and α is the third quadrant angle, then cos (15 ° - α) is equal to several

cos(15°-a) = sin(90°-(15°-a)) = sin(75°+a)
75 ° + A in the 3 / 4 quadrant, sin (75 ° + a)

It is known that sin a= 1/3, and a is the second quadrant angle, the values of COS A and Tan a are obtained

∵ A is the second quadrant angle
∴cosa