# Scale Factor

How to use the meaning of the scale factor of two similar triangles to find the missing side: 2 examples and their solutions.

## Similar

If two triangles are similar,

their shapes are the same

but their sizes are different.

So their corresponding interior angles

are the same

and their corresponding sides

are changed in the same ratio.

[ ~ ] is the similar symbol.

## Scale Factor

That ratio is the scale factor.

The scale factor means

how much the length (sides, height, etc)

has changed.

## ExampleTriangles → Scale Factor

The given triangles are similar.

See the right triangle.

Side 3 is adjacent to

a circle angle and a plane angle.

See the left triangle.

Side 2 is also adjacent to

a circle angle and a plane angle.

So 2 and 3 sides are the corresponding sides.

2 and 3 are the corresponding sides.

And the scale factor is k.

So 2⋅k = 3.

Divide both sides by 2.

Then k = 3/2.

So the scale factor k is 3/2.

## ExampleScale Factor → Missing Side

The given triangles are similar.

See the right triangle.

Side x is adjacent to

a circle angle and a square angle.

See the left triangle.

Side 8 is also adjacent to

a circle angle and a square angle.

So x and 8 sides are the corresponding sides.

8 and x are the corresponding sides.

And the scale factor is 2.

So x = 8⋅2.

8⋅2 = 16

So 16 is the answer.