Question

ABCD is a quadrilateral. If m

Answer 1

A. 9

Step-by-step explanation

The sum of the measures of the interior angles of a quadrilateral is 360. In this case, we know that angles A and D are right angles, so their measures are 90°. Also, the measure of angle B is 99° and the measure of angle C is x², so we can write an equation for x,

`90+90+99+x^2=360`

Combine like terms,

`279+x^2=360`

Subtract 279 from both sides,

`\begin{gathered} 279-279+x^2=360-279 \\ \\ x^2=81 \end{gathered}`

And take the square root of each side,

`\begin{gathered} √(x^2)=√(81) \\ \\ x=9 \end{gathered}`

Hence, the value of x is 9.