their hypotenuse are <u>parallel</u> (marked by the arrows)
This means the corresponding side lengths and angles are equal.
Therefore,
∠CDA = ∠ABC
⇒ x = 60°
<u>Question 3</u>
The <u>hypotenuse</u> is the <u>longest side</u> of a <u>right triangle</u> - the side opposite the right angle (the right angle is shown as a small square).