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Glencoe Math: Course 3, Volume 2

GM

Glencoe Math: Course 3, Volume 2 View details

3. Angles of Triangles

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Exercise 1 Page 392

The sum of the measures of the interior angles of a triangle is 180^(∘).

45^(∘)

Practice makes perfect

We want to find the measure of the angle in the given triangle.

A triangle with two known interior angles measuring 75 and 60 degrees, and the other interior angle measuring x degrees.

To find this angle measure, we will first recall a key piece of information!

Angle Sum of a Triangle
The sum of the measures of the interior angles of a triangle is 180^(∘).

With this rule, we can write an equation connecting the measures of the angles of our triangle. x^(∘)+ 75^(∘)+ 60^(∘)=180^(∘) Let's solve the equation and find the value of x. For simplicity, we will not write the degree symbol.

x+75+60=180

▼

Solve for x

Add terms

x+135=180

LHS-135=RHS-135

x=45

The measure of the third angle is 45^(∘).

triangle

Subchapter links

Guided Practice p.392

Independent Practice p.393-394

H.O.T. Problems p.394

Standardized Test Practice p.394-396

Extra Practice p.395

Common Core Review p.396