Practice30Create account

A triangle has angles 30°, 60° and 90°. Classify it by its sides.

Class 7The Triangle and its PropertiesTriangles
  • AIsosceles
  • BEquilateral
  • CScalene
  • DThe sides cannot be compared from the angles alone

Step-by-Step Solution

All three angles are different, and sides opposite different angles have different lengths, so all three sides differ — the triangle is scalene. Trap: assuming every right triangle is isosceles (only the 90°, 45°, 45° one is), or thinking angles say nothing about sides — the side-angle relationship does exactly that.
Answer: C) Scalene

Key idea: Side-angle relationship

**The longest side of a triangle is opposite the largest angle. The shortest side is opposite the smallest angle.**

In an isosceles triangle, the two equal sides face equal angles. In an equilateral triangle, all sides equal → all angles 60°.

This lets you order sides if you know the angles, or vice versa, even without computing exact values.

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

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…AD is the median from A to side BC in triangle ABC. Which statement is NOT always true?