If the diagonal of the rectangle is 20cm, the area is 25 and the root is 3cm2, the tangent value of the acute angle between the two diagonal lines is?

If the diagonal of the rectangle is 20cm, the area is 25 and the root is 3cm2, the tangent value of the acute angle between the two diagonal lines is?

rectangle
Area of inner triangle: 25 √ 3 / 4
And the two sides are 20 / 2 = 10
Isosceles triangle of
(1/2）*10*10*sin=25√3/4
So sin = √ 3 / 2
So the angle is 60 degrees
The tangent value is √ 3

If 5x-7xy-6y ^ 2 = 0, find the value of 3x / y

If 5x ^ 2-7xy-6y ^ 2 = 0, find the value of 3x / y. 5x ^ 2-7xy-6y ^ 2 = 0 (5x + 3Y) (x-2y) = 05x + 3Y = 0, the solution is: 5x = - 3Y, X / y = - 3 / 5, x-2y = 0, the solution is: x = 2Y, X / y = 2, so 3x / y = 3 * (- 3 / 5) = - 9 / 53x / y = 3 * 2 = 6

The solution equation is 0.7 * 4-5x = 0.80.8x-14.7 = 1.3 x / 2 / 3 = 2.52 * (x-0.7) = 4.8

0.7*4-5x=0.8 0.8x-14.7=1.3 x/2/3=2.5 2*（x-0.7）=4.82.8-0.8=5x 0.8x=14.7+1.3 x=2.5*2*3 2x-1.4=4.82=5x 0.8x=16 x=15 2x=1.4+4.8x=2/5 x=20 2x=6.2x=0.4 x=3.1

The area of an isosceles triangle PAB P (- 3,2) triangle PAB with a slope of 1 and a straight line intersection ellipse x ^ 2 / 8 + y ^ 2 / 4 = 1 at two points AB with ab as the bottom edge~

Let the straight line: y = x + B, intersect with the ellipse: x ^ 2 + 2 * (x + b) ^ 2-8 = 0, and get: 3 * x ^ 2 + 4bx + 2B ^ 2-8 = 0
If the key point of AB is m (m, M + b), then M = (- 4B / 3) / 2 = - 2b / 3, M + B = B / 3
And because PM is perpendicular to AB, the slope of the line PM is - 1
That is: (2-B / 3) / (- 3 + 2B / 3) = - 1, the solution is: B = 3
Straight line: y = x + 3, intersection with ellipse: 3x ^ 2 + 12x + 10 = 0, absolute value of (x1-x2) = 2 √ 6 / 3, m (- 2,1)
AB=4√3/3,PM=√2
Area = 4 √ 3 / 3 * √ 2 / 2 = 2 √ 6 / 3

Computers process information in digital form

It should be that the computer processes information by using the number code of 01, which is reflected as operation in the form of language

Simplification: 1 / (2 + √ 2) + 1 / (√ 6 + 2) + 1 / (√ 8 + √ 6) + +1/（√2012+√2010）+1/（√2014+√2012）

Original formula = (1 / 2) * (2 - √ 2 + √ 6-2 + √ 8 - √ 6 +...) +√2012-√2010+√2014-√2012）
=（1/2）*（-√2+√2014）=（√2014-√2）/2

If the derivative of the function y = f (x) is an increasing function in the interval [a, b], then the possible image of the function y = f (x) in the interval [a, b] is as follows ()
A. （1）、（3）、（4）B. （2）、（5）、（6）C. （1）、（2）、（3）D. （4）、（5）、（6）

The derivative of the function y = f (x) is an increasing function in the interval [a, b]. For any a ＜ x ′＜ x ″＜ B, f ′ (a) ＜ f ′ (x ′) ＜ f ′ (x ″) ＜ f ′ (b), that is, with the increase of X, the slope of the corresponding tangent at this point should also increase. Therefore, (1) (2) (3) satisfies the above conditions, (4) (5) (6) with the increase of X, the slope of the corresponding tangent at this point should also increase The slope of the corresponding tangent should also decrease, which is not in line with the meaning of the question

Calculation: a (a + 1) + 1 / (a + 1) (a + 2) + 1 / (a + 2) (a + 3) + + 1 / (a + 2004) (a + 2005)

1 / (a + 1) (a + 2) = 1 / (a + 1) - 1 / (a + 2) similarly: 1 / (a + 2) (a + 3) = 1 / (a + 2) - 1 / (a + 3) so: a (a + 1) + 1 / (a + 1) (a + 2) + 1 / (a + 2) (a + 3) + + 1 / (a + 2004) (a + 2005) = a (a + 1) + 1 / (a + 1) - 1 / (a + 2) + 1 / (a + 2) - 1 / (a + 3) +. + 1 / (a + 2004) - 1 / (a + 2005)

If the point P (M + 2,2m + 4) is shifted one unit to the right to p ', and P' is on the y-axis, what is the coordinate of point P '
A：（-2,0） B：（0,-2）
C：（1,0） D：（0,1）

B is the answer
After translation, p 'is on the Y axis, that is, the abscissa is 0, which means that the abscissa of P point before translation is - 1, and the ordinates of P and P' are the same, so m + 2 = - 1, M = - 3, so the ordinate 2m + 4 = - 2
It's easy to make a picture of this kind of inscription

X + 1 / 4 x = 25 to solve the equation

X + 1 / 4 x = 25
5 / 4 x = 25
X = 25 × 4 / 5
x=20