# NCERT Class 9 Solutions: Triangles (Chapter 7) Exercise 7.2 – Part 4

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Interior Angle

When two lines are cut by a third line (transversal), then the angles formed inside the lines are called Interior Angles.

Q-7 ABC is a right angled triangle in which and . Find and

Solution:

Given, and

Now, (Angles opposite to the equal sides are equal.)

Now, (Sum of the interior angles of the triangle.) (

Thus,

Q-8 Show that the angles of an equilateral triangle are each.

Solution:

Give, ABC be an equilateral triangle.(Length of all sides is same) (Sides opposite to the equal angles are equal.)

Also, (Sum of the angles of the triangle.) ( )

Therefore,

Thus, the angles of an equilateral triangle are each.