Question

11/7 - isosceles and equilateral practice
possible points: 0.8
△def is equilateral. find \overline{df}. (hint: use the angle to solve for x)
65
49
21
16

Explanation:

Step1: Use the property of an equilateral triangle

In an equilateral triangle, all angles are \(60^{\circ}\). So, \(2x + 28=60\).

Step2: Solve the equation for \(x\)

Subtract \(28\) from both sides: \(2x=60 - 28\), \(2x = 32\). Then divide both sides by \(2\): \(x=\frac{32}{2}=16\).

Step3: Find the length of \(DF\)

Since \(DF=x + 5\), substitute \(x = 16\) into the expression: \(DF=16+5=21\).

Answer:

21