# NCERT Class 9 Solutions: Triangles (Chapter 7) Exercise 7.3 – Part 3

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Altitude of triangle

In geometry, an altitude of a triangle is a line segment through a vertex and perpendicular to (i.e. forming a right angle with) a line containing the base (the opposite side of the triangle). This line containing the opposite side is called the extended base of the altitude.

Q-4 BE and CF are two equal altitudes of a triangle ABC. Using RHS congruence rule, prove that the triangle ABC is isosceles

Solution:

Given,BE and CF are two equal altitudes.

In and , (Altitudes) (Common)(Common)

Therefore, by RHS congruence condition.

Now, (by Corresponding Parts of Congruent Triangles)Thus, as sides opposite to the equal angles are equal.

Q-5 ABC is an isosceles triangle with. Draw to show that

Solution:

Given,In (AP is altitude) (Given) (Common line)

Therefore, by Right Angle-Hypostenuse-Side congruence condition.

Thus,(by Corresponding Parts of Congruent Triangles)