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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 21 Page 395

The sum of the measures of the interior angles of a triangle is $18 0^{\circ} .$

$12 0^{\circ}$

Practice makes perfect

We are told that a triangle has angles measuring $x^{\circ},$ $3 5^{\circ},$ and $2 5^{\circ} .$ We want to find the values of $x .$ To do it, let's 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 $18 0^{\circ} .$

With this rule, we can write an equation connecting the measures of the angles of our triangle.

x^{\circ} + 3 5^{\circ} + 2 5^{\circ} = 18 0^{\circ}

Let's solve the equation and find the value of

x .

For simplicity, we will not write the degree symbol.

x + 35 + 25 = 180

▼

Solve for

x

Add terms

x + 60 = 180

$LHS - 60 = RHS - 60$

x = 120

The measure of the missing angle is

12 0^{\circ} .

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