Please answer either or all of them and please show me how you solve it

Step-by-step explanation:

using pythagoras theorem

a^2 + b^2 = c^2

4^2 + y^2 = 21^2

16 + y^2 = 441

y^2 = 441 - 16

y^2 = 425

y = 13.2

a^2 + b^2 = c^2

4^2 + x^2 = 7^2

16 + x^2 = 49

x^2 = 40 - 16

x^2 = 33

x =

x = 5.7 m