Question 711151
Use the Pythagorean theorum to solve this:
{{{a^2+b^2=c^2}}}
Where a and b are the sides, and c is the hypotenuse.
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{{{3^2+b^2=5^2}}}
{{{9+b^2=25}}}
{{{b^2=16}}}
{{{highlight(b=4)}}}
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Note this is what is called a 3-4-5 right triangle. This rule applies to all similar triangles to the 3-4-5, so you can solve for the sides of this kind of triangle easily. For example, if you are given  a=6, b=8, you automatically know that c=10, since this is a "3-4-5 times 2."
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Good Luck,
tutor_paul@yahoo.com