Answer:
∠ABC = 72°
Step-by-step explanation:
When we look at the triangle carefully, we can see a bar on AC and AB. Those bars define that AC and AB are equivalent. This also means that the triangle is isosceles. Since this triangle is isosceles, the base angles of the triangle are equivalent.
⇒ AB = AC
We also know that the sum of its interior angles must be 180°.
⇒ ∠A + ∠B + ∠C = 180
Let's substitute their angle measures.
⇒ 3x + 6x + 6x = 180 [∠BAC = 3x; ∠ABC = ∠ACB = 6x]
Now, let's solve for x.
⇒ 3x + 6x + 6x = 180
⇒ 15x = 180
⇒ 15x/15 = 180/15
⇒ x = 12
Now, substitute the value of x into "6x" to find ∠ABC.
∠ABC = 6x
⇒ ∠ABC = 6(12)
⇒ ∠ABC = 72°
