In the diagram, the perimeter of the triangle is equal to the perimeter of the rectangle. What is the value of $x$ ?
(A) 8
(B) 10
(C) 11
(D) 14
(E) 15

![](https://cdn.mathpix.com/cropped/2024_04_20_46ead6524a8d61e21c51g-016.jpg?height=120&width=422&top_left_y=1699&top_left_x=1296)
The triangle is isosceles, and so the missing side length is also $12 \mathrm{~cm}$.

The perimeter of the triangle is $14+12+12=38 \mathrm{~cm}$.

The perimeter of the rectangle is given by $x+8+x+8=2 x+16 \mathrm{~cm}$.

The perimeter of the triangle is equal to the perimeter of the rectangle, and so $2 x+16=38$.

Since $22+16=38$, then $2 x=22$ and so $x=11$.

ANSWER: (C)