- A35
- B25
- C50
- D60
Step-by-Step Solution
First find the hypotenuse: → cm. Then perimeter = 15 + 20 + 25 = 60 cm. Trap: answering 35 (just the two legs) or 25 (just the hypotenuse) — the question asks for all three sides added together.
Answer: D) 60
The two legs of a right triangle measure 15 cm and 20 cm. Find the perimeter of the triangle in cm.
Class 7The Triangle and its PropertiesTriangles
Key idea: Angle sum property
**The three interior angles of any triangle sum to 180°.**
This is true for every triangle — equilateral, isosceles, scalene, right, acute, or obtuse. Use it to find a missing angle when you know the other two: third angle = 180° − (first) − (second).
Special cases:
- Equilateral: all angles equal → each is 60°.
- Right triangle: one is 90°, so the other two sum to 90° (they are complementary).
This is true for every triangle — equilateral, isosceles, scalene, right, acute, or obtuse. Use it to find a missing angle when you know the other two: third angle = 180° − (first) − (second).
Special cases:
- Equilateral: all angles equal → each is 60°.
- Right triangle: one is 90°, so the other two sum to 90° (they are complementary).
Master this chapter in 30 minutes a day.
Don't just memorise the answer — build a daily practice habit.
Practice 5 Similar Questions Free →All The Triangle and its Properties practice questions
More Class 7 The Triangle and its Properties practice
A triangle has angles 30°, 60° and 90°. Classify it by its sides.Which of these triangles is impossible to draw?Which property holds for every equilateral triangle but NOT for every isosceles triangle?In triangle ABC, angle C = 90° and angle A = 32°. Side AB is produced beyond B to a…In triangle PQR, PQ = PR and angle Q = 65°. Side QR is produced to a point S. Find angle…