Similar_Triangles

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Similar Triangles:

Similar Triangles

Similar shapes:

Similar shapes Are Enlargements of each other Corresponding angles are equal Sides are related by the same scale factor

Similar Triangles:

Similar Triangles 50º 50º 30º 30º 100º 100º Triangles are similar if matching angles remain the same size.

Show that these triangles are similar:

Show that these triangles are similar 50º 50º 10º 10º 120º 120º

To calculate a length:

To calculate a length 4 15 5 18 6 12 15 5 x 3 x 3 1 3 Scale factor 3 Scale factor 1/3

Harder example:

Harder example C A E D B Triangle ABC is similar to triangle ADE. DE is parallel to BC. Calculate the length of BC 3 6 4

Harder example:

Harder example C A B E D 3 4 6 9 9 3 x 3 12

…and then…:

…and then… A C E D B 3 6 5 ? AB & DE are parallel Explain why ABC is similar to CDE <CED = <BAC Alternate Angles <EDC = <ABC Alternate Angles <ECD = <ACB Vert Opp Angles Triangle ABC is similar to Triangle CDE

…and then…:

…and then… A C E D B 3 6 5 ? Calculate the length of DE Scale Factor = 2 AC corresponds to CE AB corresponds to DE DE = 2 x AB DE = 10cm

Summary – Similar shapes:

Summary – Similar shapes To calculate missing sides, we first of all need the scale factor We then either multiply or divide by the scale factor To show that 2 shapes are similar we can either show that all of the sides are connected by the scale factor or show that matching angles are the same

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