2D shapes from lengths, angles
for 5th grade

Identify 2D shapes from information on sides and angles

Many regular 2D shapes can be characterized in terms of the length and number of sides plus information on the angles of their vertices.

For instance, say we have a shape that has 4 equal length sides and 4 equal angles of 90 degrees. Given that it has 4 angles of 90° it must be a regular quadrilateral. Knowing that it has 4 equal length sides we can deduce that it is a square.

If you have a shape with 3 sides of unequal length and 3 angles that add up to 180 degrees, you know immediately that it has to be a triangle (internal angles of triangles add up to 180°). The fact that the sides are of unequal length means it cannot be an equilateral triangle (which has equal length sides) or an isosceles triangle (which has 2 sides the same length) so we know it must be a scalene triangle.

In this topic you are given as question a description of a shape in terms of it's sides and angles. You have to decide which shape that description applies to. The shapes that are covered include square, rectangle, different types of triangle, rhombus, parallelogram, kite, pentagon, hexagon, etc.