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Interior and exterior triangle angles

Interior and exterior triangle angles-example-1
User Jim Pedid
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1 Answer

3 votes

Answer:

∠ GHI = 17°

Explanation:

the exterior angle of a triangle is equal to the sum of the 2 opposite interior angles.

∠ HIJ is an exterior angle of the triangle , then

∠ HJI = ∠ GHI + ∠ IGH , that is

7x - 18 = 2x - 3 + 2x + 15

7x - 18 = 4x + 12 ( subtract 4x from both sides )

3x - 18 = 12 ( add 18 to both sides )

3x = 30 ( divide both sides by 3 )

x = 10

Then

∠ GHI = 2x - 3 = 2(10) - 3 = 20 - 3 = 17°

User Pixeltom
by
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