In the diagram below, ABCD is a trapezium - OCR - GCSE Maths - Question 19 - 2017 - Paper 1

Apply the sine rule:

$\frac{DE}{\sin(x)} = \frac{80\text{ cm}}{\sin(90^{\circ})}$

Substituting values, we have:

$\frac{25}{\sin(x)} = \frac{80}{1}$

This implies that.

$\sin(x) = \frac{25}{80} = 0.3125$

To find angle x, we take the inverse sine:

$x = \sin^{-1}(0.3125) \approx 18.2^{\circ}$.

Hence, the value of angle x is approximately 18.2 degrees.