Answer:
BC =

Explanation:
∆ABC is an equilateral ∆ because all three angles are equal. Therefore, all its sides would be equal also. This means AB = BC = AC
Thus, let's find the value of x.

Collect like terms




Multiply both sides by 4


Divide both sides by -5

AB = BC = AC
Therefore,
BC =

Plug in the value of x
BC =

BC =

BC =

BC =
