GCSE Maths Practice: triangles-and-quadrilaterals

Question 4 of 10

This question focuses on calculating the missing angle in a quadrilateral.

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\( \begin{array}{l}\text{A quadrilateral has three angles measuring } 90^\circ, 95^\circ, \text{ and } 90^\circ.\\ \text{Find the size of the fourth angle.}\end{array} \)

Choose one option:

Add known angles and subtract from 360° to find the missing angle.

In any quadrilateral, the sum of interior angles is always 360°. To find a missing angle, add the given angles and subtract the sum from 360°. For example, given three angles 90°, 95°, and 90°, sum = 275°. The missing angle is 360° - 275° = 85°. Understanding this principle helps solve geometry problems, calculate unknown angles, and analyze quadrilateral shapes. Students should practice labeling quadrilaterals, summing known angles, and calculating missing angles. This knowledge also helps with composite shapes, interior and exterior angle calculations, and solving real-life geometry problems. Familiarity with angle sums is essential for GCSE exam questions.