Answer:
The length of BC = 28 units
Step-by-step explanation:
* In triangle ABC
∵ Angles B and C are congruent
∴ m∠B = m∠C
* In any triangle if two angles are equal in measure, then the triangle is isosceles means the two sides which opposite to the congruent angles are equal in length
∴ AB = AC
∵ AB = 4x - 7
∵ AC = 2x + 7
∴ 4x - 7 = 2x + 7 ⇒ collect like terms
∴ 4x - 2x = 7 + 7
∴ 2x = 14 ⇒ divide both sides by 2
∴ x = 14 ÷ 2 = 7
* Now we can find the length of BC
∵ The length of BC = 4x ⇒ substitute the value of x
∴ The length of BC = 4 × 7 = 28 units
