- A40
- B36
- C80
- D44
Step-by-Step Solution
Base angle = 180 - 110 = 70°. Both base angles are 70, so apex = 180 - 140 = 40°.
Answer: A) 40
In an isosceles triangle, an exterior angle at one base vertex is 110°. The vertex (apex) angle is (in degrees):
Class 9Properties of Isosceles TrianglesGeometry — Triangles
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 Properties of Isosceles Triangles practice questions
More Class 9 Properties of Isosceles Triangles practice
In a triangular park ABC in Pune the gardener notes that two paths AB and AC are of…Arjun makes an isosceles flag in which the two slanting sides are equal. He says the…In triangle PQR, PQ = PR. The bisector of angle Q and the bisector of angle R are drawn.…In triangle ABC, AB = AC. D is the midpoint of BC. By which rule are triangles ABD and…An isosceles triangle has its vertex angle equal to 4 times each base angle. What is the…