1. Three angles of a quadrilateral are 90°, 100°, and 75°. Find the fourth.
- A95°
- B85°
- C105°
- D265°
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Answer: A) 95°
Sum = 360°. 360 − (90 + 100 + 75) = 360 − 265 = 95°.
Class 8 Understanding Quadrilaterals — practice questions with answers
Quadrilaterals · 5 sample questions from the school syllabus. Try each one, then open the answer and the worked solution.
2. What is the sum of the interior angles of any quadrilateral, in degrees?
- A395
- B325
- C720
- D360
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Answer: D) 360
Using (n − 2) × 180 with n = 4 gives (4 − 2) × 180 = 360°.
3. Which quadrilateral has all four sides equal but its angles need not be 90°?
- ARhombus
- BRectangle
- CSquare
- DTrapezium
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Answer: A) Rhombus
A rhombus has all four sides equal, but its angles are 90° only when it is also a square. A rectangle has 90° angles but unequal sides in general.
4. The measure of each interior angle of a regular pentagon is:
- A108°
- B120°
- C90°
- D72°
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Answer: A) 108°
Sum = (5 − 2) × 180 = 540°. Each angle = 540 / 5 = 108°.
5. An exterior angle of a regular polygon is 72°. How many sides does the polygon have, and name it.
- A4
- B10
- C6
- D5
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Answer: D) 5
Number of sides = 360 / 72 = 5. A regular polygon with 5 sides is a regular pentagon.
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