Answer:
4
Step-by-step explanation:
use the Pythagoras' theorem
formula for an ABC triangle( right angled)
AB is height
BC is hypotenuse
CA is length
[tex]BC^{2}[/tex] = [tex]AB^{2}[/tex] + [tex]CA^{2}[/tex]
in your case
AB is 7
BC is 8
CA is unknown so we write x
[tex]8^{2}[/tex]=[tex]7^{2}[/tex]+[tex]x^{2}[/tex]
64=49+[tex]x^{2}[/tex]
64-49=[tex]x^{2}[/tex]
15=[tex]x^{2}[/tex]
[tex]\sqrt{15}[/tex] =x
3.87=x
4=x
