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

Interior Angle

Give interior angle of two parallel line when two lines are cut by a third line lthen made a,b,c,d angle

Give Interior Angle

Give interior angle of two parallel line when two lines are cut by a third line lthen made a,b,c,d 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 A=90° and AB=AC . Find B and C.

Solution:

Give ABC is a right angled triangle in which ∠A = 90° and AB = AC

Give ABC Is a Right Angled Triangle

Give ABC is a right angled triangle in which ∠A = 90° and AB = AC

Given, A=90° and AB=AC

  • Now, AB=AC B=C (Angles opposite to the equal sides are equal.)

  • Now, A+B+C=180° (Sum of the interior angles of the triangle.) 90°+2B=180° ( B=C) 2B=90°B=45°

  • Thus, B=C=45°

Q-8 Show that the angles of an equilateral triangle are 60° each.

Solution:

Give ABC be an equilateral triangle each of angle is 60

Give ABC Be an Equilateral Triangle.

Give ABC be an equilateral triangle each of angle is 60

Give, ABC be an equilateral triangle. BC=AC=AB (Length of all sides is same) A=B=C (Sides opposite to the equal angles are equal.)

  • Also, A+B+C=180° (Sum of the angles of the triangle.) 3A=180° ( A=B=C ) A=60°

  • Therefore, A=B=C=60°

  • Thus, the angles of an equilateral triangle are 60° each.

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