The diagram shows triangle ABC, with AB=xcm,AC=(x 2)cm,BC=2sqrt(7)cm and angle CAB=60°. (i) Find the value of x. [4] (ii) Find the area of triangle ABC, giving your answer in an exact form as simply as possible.

Respuesta :

To find the value of x in triangle ABC, we can use the cosine rule.

To find the value of x, we can use the cosine rule. According to the cosine rule, in a triangle with sides a, b, and c, and angle A opposite side a, we have the formula: c² = a² + b² - 2ab * cos(A). We know that AB = x cm, AC = (x+2) cm, and BC = 2√7 cm. Also, angle CAB = 60°. Applying the cosine rule, we have: (x+2)² = x² + (2√7)² - 2(x)(2√7) * cos(60°).

Simplifying the equation, we get: x² + 4x + 4 = x² + 28 - 4x(√7). Rearranging the terms, we have: 8x(√7) = 24 or x(√7) = 3. Dividing both sides by √7, we get: x = 3/√7.

Therefore, the value of x is 3/√7 cm.