# Triangle: Interior Angles

How to solve the interior angles of a triangle: formula, 1 example, and its solution.

## Formula

m∠1 + m∠2 + m∠3 = 180

∠1, ∠2, ∠3: Interior angles of a triangle

## Example

Solution

Solution (Detail)

These three angles

are the interior angles of the triangle.

So

[60] + [3x + 30] + [7x + 10] = 180.

3x + 7x = 10x

60 + 30 + 10 = +100

Move +100 to the right side.

Then 10x = 80.

Divide both sides by 10.

Then x = 8.

So x = 8.