Answer:
x = 36
a = 25
Step-by-step Explanation
By Pythagoras Theorem:
[tex]x = \sqrt{ {39}^{2} - {15}^{2} } \\ \\ x = \sqrt{1,521 - 225} \\ \\ x = \sqrt{1,296} \\ \\ x = 36 \\ \\ a = \sqrt{ {20}^{2} + {15}^{2} } \\ \\ a = \sqrt{400 + 225} \\ \\ a = 25 \sqrt{625} \\ \\ a = 25[/tex]
