Solid geometry is parallel to the intersection line, and solid geometry proves that the line and sur

You can do perpendiculars by doing it.

Take a point on the A line to make the perpendicular lines of the two planes, and the A line is parallel to the two planes, so the two perpendicular lines are made perpendicularly, so the A line is perpendicular to the plane composed of two perpendicular lines. The intersection line l belongs to , and also belongs to , so the two perpendicular lines are perpendicular, and thus the plane is formed vertically.

Both lines are perpendicular to the same plane, so they are parallel.

Because :a, through a makes a plane r, and intersects the straight line b because: a

So: a b

Because: plane plane = l

So: l b

So: a l

By the counter-argument, if A and L are not parallel, and A, A, then a line B can be made parallel to A and intersected by L in the plane, and the plane P, determined by A, and the intersection of the plane through A, that is to say, A is not parallel to the plane. It doesn't match the title.

This idea, as long as you make a plane, is it simpler?

It's actually a theorem.

If you really want to prove it, you will be disproved, and if he intersects with L, then he must intersect with both sides, which is obviously in conflict with his parallel to both sides.

a‖α，a‖β

Make a line m parallel to a

Therefore m is parallel , parallel

am plane parallel plane , plane

Plane Plane = l

l Parallel AM plane.

l parallel a This is the easiest way, it is the Guangdong version.

Conclusions that can be understood at a glance are simple but often difficult to understand by counter-proof!

This method is simple enough, and it is easy to find a simple way only by using complex problems with linear and surface properties and parallel axioms.

There's a theorem to illustrate it, and it's going to be fast.

It is relatively simple to use the counter-argument method.

If you want someone to help you with your homework, just say it. Why bother to add two sentences at the end?

1. A line outside the plane is parallel to a line in the surface, or there is an intersection line on both sides to emphasize the outside and inside of the plane.

2. The distance from the two points to the surface is equal on the straight line outside the plane, emphasizing the outside of the plane.

3. Prove that there is no intersection between the line and the surface.

4. Counter-evidence (the line intersects with the surface, and then overthrows).

5. The space vector method proves that the parallel vector of the line and the vector in the plane (x1x2-y1y2=0).

In solid geometry, the angles between two parallel lines and the third line are not necessarily equal. It depends on the specific geometry.

For example, in a parallel plane, two parallel lines are equal to the intersection of the two cluster head planes. However, if the third line is not between these two planes, then its angle to the two planes can be unequal.

In three-dimensional space, two parallel lines can be located in different planes or in the same plane but do not intersect with a third line, so their angles to the three lines of the pure stove can be unequal. It depends on the relative position and direction of the three straight lines.

Your confusion may be like this, generally you choose a special point on an edge (such as BC in the figure) (as M in the figure) to get the intersection point D of the straight line AM and the plane, and connect CD to get the intersection line of the plane ABC and the plane.

If the intersection of the plane ABC and the plane does not have one in the graph, you can extend the two edges of the ABC to get two different intersection points with the plane, and connect the two intersection points.

According to the axioms, the intersection of two planes is a straight line, and two points determine a straight line, so as long as two different common points of the two planes are found, they are connected to the intersection of the two planes.

1) Let the center of ABCD be O, C1 and O, which are both on the surface ACC1A1 and on the surface BC1D, so that even C1O is the intersection of the two planes;

2) Let the center of CDD1C1 be P, and verify that OP is the intersection line.

One of the property theorems of plane parallelism: if two planes are parallel, then any line on one plane is parallel to the other.

Solution: Because the plane is flat and the straight line l plane, the straight line l plane.

Parallel: If a straight line is parallel to a straight line in a plane, and the line is outside that plane, then the line is parallel to the plane. If two straight lines in one plane are parallel to two straight lines in another plane, then the two planes are parallel.

If two planes are parallel, then any line in one plane is parallel to the other. Perpendicular If a straight line is perpendicular to two intersecting lines in a plane, then the line is perpendicular to this plane. If a straight line is perpendicular to a plane, then the plane passing through the line is perpendicular to the other plane.

If two planes are perpendicular, then a line within one of them is perpendicular to the intersection of the two planes, then the line is perpendicular to the other plane. Two straight lines perpendicular to the same plane are parallel to each other.

It is sufficient to prove that the line is perpendicular to the normal of the polygon.

Find a line parallel to a known line in the plane, and if a line A is parallel to another line B, then A must be parallel to any plane that passes through the line B (without passing A).

1. Prove that the line is parallel to a line on the plane.

2.Prove that the jumper is perpendicular to the normal of the plane.

3.Prove that the parallel lines of this line are parallel to the plane.

If you don't know how to use geometric methods, you can establish a Cartesian coordinate system with vectors, although it is a bit troublesome to calculate, but the idea is still very simple.

Method 1: If a plane passes through this line and intersects the plane sought, and the intersecting line is parallel to the line.

Then the line is parallel to the plane.

Method 2: Prove that the faces are parallel.

This shows that the lines and planes are parallel.

There are many methods, the regularity is very strong, and it is necessary to have a good spatial imagination, which can be done by constructing figures, translating lines, etc.