Respuesta :

Mathunga
Use the Pythagorean Theorem. a^2+ b^2=c^2.
In this case, it is c^2-b^2=a^2, so your answer is 4.686 mm^2. Round if you need to.
Pythagoras Theorem:

[tex]\boxed {\boxed {a^2 + b^2 = c^2}}[/tex]

Apply Pythagoras Theorem:
[tex]5.2^2 + b^2 = 7^2[/tex]

Take away 5.2² from both sides:
[tex]b^2 = 7^2 - 5.2^2[/tex]

Evaluate the Right Hand Side:
[tex]b^2 = 21.96[/tex]

Square root both sides:
[tex]b = \sqrt{21.96} [/tex]

Evaluate the Right Hand Side:
[tex]b = 4.7 [/tex]

[tex]\boxed{\boxed{\text{Answer = 4.7 mm}}}[/tex]