Question

Some question and their alternative answer are given. Select the correct alternative.

 In ∆ABC, AB = \[6\sqrt{3}\] cm, AC = 12 cm, BC = 6 cm. Find measure of ∠A.

विकल्प

• 30°

• 60° 

• 90°

• 45°

Answer 1

In ∆ABC, AB = \[6\sqrt{3}\] cm, AC = 12 cm, BC = 6 cm.

AB² =  `(6sqrt(3))`² = 108
AC² = (12)² = 144
BC² = (6)² = 36

108 + 36 = 144

In a triangle, if the square of one side is equal to the sum of the squares of the remaining two sides, then the triangle is a right angled triangle.

In a right angled triangle, if one side is half of the hypotenuse then the angle opposite to that side is 30°.
Here, BC is half of AC.

Thus, measure of ∠A is 30°

Hence, the correct option is 30°