# Inscribed Quadrilateral

How to solve inscribed quadrilateral problems: formula, example, and its solution.

## Formula

In an inscribed quadrilateral,

there are two pairs of opposite angles.

(left figure, right figure)

For each pair,

the opposite angles are supplementary.

So m∠[blue] + m∠[green] = 180.

Supplementary angles

## Example

The given angles are the interior angles

of an inscribed quadrilateral.

These two angles are the opposite angles.

So *x* + 100 = 180

Move +100 to the right side.

Then *x* = 80.

These two angles are also the opposite angles.

So 70 + *y* = 180.

Move 70 to the right side.

Then *y* = 110.