Question

The area of a triangle is 12 sq. cm. two sides are 6 cm and 12 cm. the included angle is :

Answer 1

Given:

The area of a triangle is 12 sq. cm. two sides are 6 cm and 12 cm.

To find:

The included angle

Solution:

We use a formula including area, side and angle of a triangle, given by,

Area = ab/2 × sin C

12 = (6 × 12) / 2 × sin C

12 × 2 = (6 × 12) × sin C

24 = 72 × sin C

sin C = 24 / 72

sin C = 2 / 6 = 1 / 3

⇒ C = sin^{-1} (1/3)

∴ C = 19.47°