Properties of triangles and Pythagoras Quiz - ICSE Class 7 Mathematics
Free practice quiz: Properties of triangles and Pythagoras (ICSE Class 7 Mathematics). 56 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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In triangle ABC, if angle A = 70 degrees and angle B = 50 degrees, what is the measure of angle C?
- 40 degrees
- 50 degrees
- 60 degrees
- 70 degrees
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Answer: C. 60 degrees
The sum of angles in a triangle is always 180 degrees. Therefore, angle C = 180 - (angle A + angle B) = 180 - (70 + 50) = 180 - 120 = 60 degrees.
If the sides of a triangle are 9 cm, 12 cm, and 15 cm, what is the nature of the triangle?
- Acute-angled
- Obtuse-angled
- Right-angled
- Cannot form a triangle
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Answer: C. Right-angled
We check if the Pythagorean theorem holds: 9² + 12² = 81 + 144 = 225. And 15² = 225. Since 9² + 12² = 15², it is a right-angled triangle.
What is the perimeter of a triangle with sides 6 cm, 8 cm, and 10 cm?
- 20 cm
- 24 cm
- 30 cm
- 36 cm
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Answer: B. 24 cm
The perimeter of a triangle is the sum of the lengths of its three sides. Perimeter = 6 cm + 8 cm + 10 cm = 24 cm.
If a triangle has sides 5 cm, 8 cm, and 11 cm, which statement is true?
- It is an equilateral triangle.
- It is an isosceles triangle.
- It is a scalene triangle.
- It cannot form a triangle.
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Answer: C. It is a scalene triangle.
A scalene triangle has all sides of different lengths. Since 5 cm, 8 cm, and 11 cm are all different, the triangle is scalene. Also, 5+8 > 11 (13>11), satisfying the triangle inequality.
In triangle ABC, if angle A = 50 degrees and angle C = 80 degrees, what is the measure of angle B?
- 40 degrees
- 50 degrees
- 60 degrees
- 70 degrees
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Answer: B. 50 degrees
The sum of angles in a triangle is 180 degrees. Angle B = 180 - (angle A + angle C) = 180 - (50 + 80) = 180 - 130 = 50 degrees. This makes the triangle isosceles.