Question

my second question is little bit hard

Answer 1

here 25*25=625
7*7=49
√625-49=√576
24
done by Pythagoras theorem

Answer 2

In this ques you have to use pytagorem triplet
(H)^2=(L)^2+(L)^2
(25)^2=(7)^2+(L)^2
625=49+(L)^2
625-49=(L)^2
576=(L)^2
(24)^2=(L)
24=I
SO BC=24