Edexcel IGCSE Math A 4.1.C triangle angle properties

Practise triangle-angle questions by adding the known angles, using the 180-degree total and applying exterior-angle relationships.

Exam points

Use the angle sum of a triangle to calculate a missing interior angle.
Apply the exterior angle property where an outside angle equals two opposite interior angles.

[Maximum number: 3]

Diagram NOT accurately drawn

ABC is a straight line.

Work out the value of y

You must show your working.

$\frac{180}{3}=60$ 360-(105+125+60)=70

Final answer:
70

Marking guidance:
- M1 for an angle of $60^\circ$ in the triangle
- M1 for a correct complete method
- A1 for 70

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4.1.C The exterior angle of a triangle property and the angle question 1