If a line is parallel to two intersecting planes, then the line is parallel to their intersecting lines

If a line is parallel to two intersecting planes, then the line is parallel to their intersecting lines

To the contrary:
Let the line be m, the intersection be n, and the two planes be a and B respectively
Let m n intersect at P
Because m n intersects P
So m intersects plane a where n is
And because m is parallel to plane a
So m does not intersect any line on plane a
Contradiction with hypothesis
So m is parallel to n
Get proof

If it is proved that a line is parallel to two intersecting planes, then the line is parallel to the intersection of two planes

L / / M1 L / / m2 M1 intersects m2 at l0
Take point P on l0 and make parallel lines L1 and L2 of L on M1 and M2 respectively
Then l / / L1 L / / L2, so L1 / / L2
And L1 and L2 intersect at point P, so L1 and L2 coincide, that is l0

Three planes intersect each other. How to prove that the intersecting lines intersect at a point or are parallel
It is necessary to use the plane and plane position relationship of compulsory 2 in senior high school
Leave at six
Hope to get the answer before that

Planes a / B / C intersect each other
A. B, to L,
The relationship between L and C is only intersection and parallelism
If it intersects, then
The intersection of C and a is on B, that is, the intersection of three planes
If parallel,
Then, l is parallel to the intersection of a and C,
Similarly, it is parallel to the intersection of B and C
That is, three lines are parallel

From 3x + 5 = 10, the basis of 3x = 10-5 is obtained

If you subtract 5 from both sides, the equation holds

Given that P: x2-8x-20 > 0, Q: x ^ 2-2x + 1-A ^ 2 > 0 (a > 0), if P is not a necessary and sufficient condition for non-Q, the value range of positive real number a is obtained
If there is no a > 0,

The non-p: x ^ 2-8x-20 ≤ 0 solution is: - 2 ≤ x ≤ 10
Non Q: x ^ 2-2x + 1-A ^ 2 ≤ 0 (a > 0)
Let f (x) = x ^ 2-2x + 1-A ^ 2 (a > 0)
Then the opening of F (x) is upward and the axis of symmetry is x = 1
Because non-p is a sufficient and unnecessary condition for non-Q, then it is obvious that the range of solution set of non-Q should be larger than [- 2,10], then
Then f (- 2) = 9-A ^ 2

9 of 8 - (13 of 12 + 5 of 8) + 15 of 12

9 / 8 - (13 / 12 + 5 / 8) + 15 / 12
=（9/8-5/8）+（15/12-13/12）
=1/2+1/6
=2/3
If you don't understand this question, you can ask,

The equation of a line with a slope of 34 and a circumference of 12 of a triangle surrounded by two coordinate axes is______ ．

Let the linear equation be y = 34x + B, let x = 0, then y = B; let y = 0, then x = - 43b. | | + | - 43b | + B2 + 16b29 = 12, | | + 43 | + 53 | - B | = 12, | - B = ± 3. The obtained linear equation is y = 34x ± 3, that is, 3x-4y + 12 = 0, or 3x-4y-12 = 0, so the answer is 3x-4y + 12 = 0, or 3

31+32+33+34+35+36+37+38+39

25577

Sum function of power series
Find the sum function of the following power series:
∑（∞ n=1） (2n-1)x^(2n-2)/2^n
∑（∞ n=1） x^(2n-1)/2^n= x/(1-x^2/2)
How did you get it?

∑（∞ n=1） x^(2n-1)/2^n= x/(1-x^2/2)
Derivation on both sides of X
Σ (∞ n = 1) (2n-1) x ^ (2n-2) / 2 ^ n = derivative X / (1-x ^ 2 / 2)

What is 2000 minus 65?

1935