# SPACE

### 3D - The real dimensions

## Objectives

**- Line parallel to a plane**

**- Parallel planes**

**- Line perpendicular to a plane**

**- Perpendicular planes**

**- Determination of angle between 2 planes**

**- Mediator plane**

**- Axis of a circle**

**- Bisector plane**

## Line Parallel to A Plane

How to prove?

Prove the line is parallel to a line in the plane.

## Parallel Planes

## Line Perpendicular to a Plane

## Determination of angle between 2 intersecting planes

2. Select a straight line in first plane perpendicular to the common line.

3. Select a straight line in second plane perpendicular to common line.

The angle in that between the first determined straight line and the second.

## Mediator Plane

A mediator plane is a plane perpendicular to a segment at its midpoint.

Any point on the mediator plane is equidistant to the extremities of the segment.

How to prove it?

M1: Prove 3 points on the plane equidistant to the extremities of the segment.

M2: 1) D*[AB]

2) DA=DB, OA=OB, CA=CB

3) (DOC) mediator plane