Page 80 - NUMINO Challenge_B2

Basic Concepts Folding and Angles

If a piece of rectangular paper is folded as shown below, angles marked with
the same shapes are equal.

Example Triangle EFG is made by folding rectangle ABCD. Explain why
triangle EFG is an isosceles triangle.

HI

A EF D
BG C

Class Notes HI

Rectangles ABGE and HIGE are the same. Label the
corresponding angles of both rectangles.

A EF D
B G C

HI

Angles EGB and are alternate angles,

therefore they are equal.

A EF D
B G C

Since lines and EF are equal, triangle EFG is an HI
triangle.

A EF D
B G C

Shapes 77