Help anyone can help me do the question,I will mark brainlest.

Answer:
<ADC=90
therefore AC= 20 using Pytagoras
BAC is a right angle triangle because it belongs to the Pytagoras theorem:25,20,15 i.e 25²=15²+20²
3) I DON'T THINK PQR IS A RIGHT ANGLE TRIANGLE because it doesn't belong to the Pytagoras triple.