Question

find the value of x.

Explanation:

Step1: Recall triangle angle sum property

The sum of angles in a triangle is \(180^{\circ}\).

Step2: Use isosceles triangle property

Since two sides are equal (marked with same tick - marks), \(\angle D=\angle E = x\).

Step3: Set up equation

\(x + x+90^{\circ}=180^{\circ}\) (because \(\angle F = 90^{\circ}\)). Simplify to \(2x=180^{\circ}-90^{\circ}\). Then \(2x = 90^{\circ}\), so \(x=\frac{90^{\circ}}{2}\).

Answer:

\(45\)