Question

"Question 7 ABC is a right angled triangle in which ∠A = 90º and AB = AC. Find ∠B and ∠C.

Class 9 - Math - Triangles Page 124"

Answer 1

Use the result that angles opposite to equal sides are equal and then apply the property that sum of angles of a triangle is 180° to get a required angles.

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Solution:


Given,
∠A = 90° & AB = AC
Then,
⇒ ∠B = ∠C
[Angles opposite to the equal sides are equal]

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

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Hope this will help you...

Answer 2

Actually a right angls has one angle as 90°. The angle sum property of the triangle is 180°.They have also give that other two angles are equal.So,
90+2x=180
2x=90
x=45
Therefore,angle B and angle C is 45°