As shown in the figure, given the acute angle α, make an angle so that it is equal to 180 ° - 2 α

As shown in the figure, given the acute angle α, make an angle so that it is equal to 180 ° - 2 α

Draw an isosceles triangle, two base angles for the letter, the remaining top angle is 180-2 that letter angle!

If ∠ A is known to be an acute angle and Cosa ≤ 12, then the range of ∠ A is______ ．

∵ cos60 ° = 12, the cosine function value decreases with the increase of angle, ∵ when Cosa ≤ 12, ∵ a ≥ 60 °, and ∵ A is an acute angle, ∵ 60 °≤ ∵ a < 90 °. So the answer is: 60 °≤ a < 90 °

The test of 8x + 19 = 51

8x + 19 = 51, 8x = 32, x = 4 substitute x = 4 into the original equation, the equation holds, so x = 4 is the following of the original equation

Find the tangent equation of Y power of implicit function E minus xy = e at point (0,1)

e^y-xy=e
Left right derivative (dy / DX) e ^ Y-Y x (dy / DX) = 0
Generation (0,1) gives dy / DX = e ^ (- 1) = K
Y-1 = KX gives y = Xe ^ (- 1) 1
Pure oral calculation may not be right

How to solve 4 (x + 18) = 7x?

4x+72=7x
7x-4x=72
3x=72
x=24

If the image of the function y = sin2x + acosx is symmetric with respect to x = - π / 8, what is the real number a

Use the special value substitution method
From the theme
f(0)=f(-π/4)
0+a=-1+√2/2a
a=-2-√2/2

A number is four ninths of its reciprocal. What's the number

This number is X
x=1/x*4/9
x²=4/9
x=±2/3

Solving the bivariate linear equation 2x-3y / 4 + 2 (x + 2Y) / 5 = 1 3 (2x-3y) / 4-x + 2Y / 5 + 4 = 0

(2x-3y) / 4 + 2 (x + 2Y) / 5 = 1 3 (2x-3y) / 4-x + 2Y / 5 + 4 = 0 simplify to 18x + y = 20 30x-37y = - 80 from equation 1 can get y = 20-18x, replace equation 2 to get 30x-37 (20-18x) = - 80, solve to get x = 10 / 11, bring back to equation 3 to get y = 40 / 11, so x = 10 / 11 y = 40 / 11. If you don't understand, please ask

If the function f (x) = 2 ^ x + x-4 has and only has one zero point in the interval (m, n) (Mn is two consecutive integers), then M=

f(1)=2+1-3=-10
So there is at least one zero between (1,2)
So m = 1

The line 3x + 4Y + 3 = 0 intersects with the circle x ^ 2 + y ^ 2 + 4Y = 0, and the equation for finding the vertical bisector of line AB at two points a and B

x²+y²+4y=0
x²+y²+4y+4=4
x²+(y+2)²=2
So the center of the circle is (0, - 2)
If AB is a chord, then the vertical bisector of AB must pass through the center of the circle
Because the line is perpendicular to AB, let ax + by + C = 0
Then 3A + 4B = 0, let a = 4, B = - 3
Substituting (0, - 2)
-2×（-3）+c=0,c=-6
The linear equation is 4x-3y-6 = 0