The internal angle sum of a quadrilateral is :
C. 360°
The sum of internal angles of a polygon is determined by a formula :
![\longmapsto (n - 2) × 180°](https://img.qammunity.org/2022/formulas/mathematics/middle-school/zku6gd11r8rcu7bj3njp3mlz94tmt9cfcg.png)
where n represents number of sides.
In a quadrilateral there are four sides,
So, plugging 4 in the formula :
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![\mathrm{ \#TeeNForeveR}](https://img.qammunity.org/2022/formulas/mathematics/college/fftbih758bh06uidf26zux05qrzvkqzy7r.png)