math
3rd Grade - Geometry

3rd Grade lesson

4 - Geometry


Here are few notions of geometry you should know...


Straight lines, semi-straight lines, and segments

The straight line
The segment
The semi-straight line
rectangular triangle
rectangular triangle
rectangular triangle
A straight line is a line with no beginning and no end, and therefore infinitely long.
A segment is a line with two boundaries (or vertices).
A semi-straight line is a line which has a boundary (or vetex) on one side and is infinite on the other side.


Angle

An angle is formed by two semi-straight lines with same vertex .

angle

Straight angle

A right angle is an angle which has the same shape as angles in squares or rectangles.

angle

Parallel, perpendicular lines

Two straight lines are parallel if they never intersect.
Two straight lines are perpendicular if they intersect with a right angle.
The yellow lines are parallel
parralel lines
the green lines are perpendicular
perpendicular lines


The parallelogram

A parallelogram is a 4-edges figure with parallel opposite edges. angle

Some triangles

Right-angled triangle
Isosceles triangle
Equilateral triangle
rectangular triangle
rectangular triangle
rectangular triangle
A right-angled triangle is a triangle with a right angle
An isosceles triangle is a triangle with two edges of the same length
An equilateral triangle is a triangle with three edges of the same length



See also : geometry on fmaths.com



>>> Spatial geometry >>>


3rd Grade Geometry

problems