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Constructions to Know
Geometry
Facts about lines and triangles
Vertically opposite angles are equal in measure
Straight line adds to 180°
A+B=180°
Alternate angles are equal in measure
(when you have 2 parallel lines and line
going through them-angles inside lines)
Corresponding angles are equal in measure
(they are on the top of parallel lines or on the bottom
either side)
Angles in a triangle add to 180°
The exterior angle of a triangle is equal to
the 2 interior opposite angles
<x=<a+<b
If 2 sides of a triangle are equal in measure the angles opposite those
sides are equal in measure called isosceles triangle.
In an equilateral triangle all the sides are equal all the angles are
equal to 60°.
Facts about parallelograms
Opposite angles and sides in a parallelogram are equal in
measure.
Adjacent angles add to 180°
< A + < D = 180°
<B + < C =180°
When a diagonal is drawn, alternate angles are equal. The
diagonal does not bisect the corner angles.
A=C B=D
Example
Example
A
D
C
D
Example
Example
Example