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McGraw Hill Integrated II, 2012

MH

McGraw Hill Integrated II, 2012 View details

1. Angles of Triangles

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Exercise 20 Page 340

Use the Triangle Exterior Angle Theorem.

33

Practice makes perfect

We want to find the missing angle of the given triangle. In order to do so, we will use the Triangle Exterior Angle Theorem. This theorem tells us that the measure of an exterior angle is equal to the sum of its two remote interior angles.

Now, let's apply this theorem to the given triangle.

Notice that there is an angle denoted with a square. It means it is a right angle whose measure is 90^(∘).

Now, let's apply the theorem to the given triangle. The sum of the measures m∠ 4 and 90^(∘) will give us the measure of the third angle, 123 ^(∘). m∠ 4 + 90=123 ⇒ m∠ 4=33

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Exercises p.339-343