Test your understanding of triangle classification.
Try to answer the questions before checking the answers at the bottom of the page.
Question 1
A triangle has angles \(30^\circ, 60^\circ, 90^\circ\).
What type of triangle is it?
A) Acute
B) Right
C) Obtuse
Question 2
A triangle has angles \(50^\circ, 60^\circ, 70^\circ\).
What type of triangle is it?
A) Acute
B) Right
C) Obtuse
Question 3
A triangle has sides \(5, 5, 5\).
What type of triangle is it?
A) Scalene
B) Isosceles
C) Equilateral
Question 4
A triangle has sides \(4, 6, 7\).
What type of triangle is it?
A) Scalene
B) Isosceles
C) Equilateral
Question 5
Can the sides \(1, 2, 3\) form a triangle?
A) Yes
B) No
Question 6
A triangle has angles \(120^\circ, 35^\circ\), and \(25^\circ\).
What type of triangle is it according to its angles?
A) Acute
B) Right
C) Obtuse
Question 7
A triangle has sides \(6, 6,\) and \(9\).
What type of triangle is it according to its sides?
A) Scalene
B) Isosceles
C) Equilateral
Question 8
What is the measure of each angle in an equilateral triangle?
A) \(45^\circ\)
B) \(60^\circ\)
C) \(90^\circ\)
Question 9
Can the side lengths \(4, 5,\) and \(8\) form a triangle?
A) Yes
B) No
Question 10
A triangle has angles \(45^\circ\), \(45^\circ\), and \(90^\circ\).
Which description is correct?
A) Right and isosceles
B) Acute and scalene
C) Obtuse and equilateral
Answers
- B – Right triangle (contains a \(90^\circ\) angle)
- A – Acute triangle (all angles less than \(90^\circ\))
- C – Equilateral triangle (all sides equal)
- A – Scalene triangle (all sides different)
- B – No because \(1 + 2 = 3\), which does not satisfy the triangle inequality rule.
- C – Obtuse triangle because one angle is greater than \(90^\circ\).
- B – Isosceles triangle because two sides are equal.
- B – \(60^\circ\).
- A – Yes, because the sum of any two sides is greater than the third side.
- A – Right and isosceles because it has a \(90^\circ\) angle and two equal angles.
Practice
- Take the Quiz (Current page)