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Big Ideas Math Geometry, 2014

BI

Big Ideas Math Geometry, 2014 View details

1. Angles of Triangles

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Exercise 15 Page 236

Consider the Exterior Angle Theorem.

m∠ 2=139^(∘)

Practice makes perfect

Let's analyze the given triangle.

We can see that the interior angles are 75^(∘) and 64^(∘). According to the Exterior Angle Theorem, the measure of an exterior angle of a triangle is equal to the sum of the measures of the two nonadjacent interior angles. This allows us to write an equation. 64+75=m∠2 Now, we can find the measure of ∠ 2.

64+75=m∠2

Add terms

139=m∠2

Rearrange equation

m∠2=139

The measure of ∠ 2 is 139^(∘).

Subchapter links

Communicate Your Answer p.231

Monitoring Progress p.232-235

Exercises p.236-238