Similar triangles

Intros

Lessons

What are similar triangles?
- common angles
- common ratios (scale factors)
What is a scale factor?

Examples

Lessons

Determine if the triangles are similar.

Which triangles are similar?

Triangle	Angles	Sides
$\Delta$ ABC	$\angle$ A =90° $\angle$ B =45° $\angle$ C =45°	AB=12.5 BC=17.7 AC=12.5
$\Delta$ DEF	$\angle$ D =90° $\angle$ E =45° $\angle$ F =45°	DE=10 EF=14.2 DF=10
$\Delta$ GHI	$\angle$ G =90° $\angle$ H =60° $\angle$ I =30°	GH=13.8 HI=27.6 GI=23.9
$\Delta$ JKL	$\angle$ J =90° $\angle$ K =45° $\angle$ L =45°	JK=5 KL=7.1 JL=5

$\Delta$ ABC and $\Delta$ DEF are similar triangles. Calculate the missing side length.
A wood made ramp needs one supporting beam (y) for reinforcement. How long should the supporting beam be?

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