is it a right triangle (has a right angle)? if so, you just apply the Pythagorean Theorem. (skip to the bottom if you don't care)
a²+b²=c²
substitute A and B for the two lines (legs) that make up the right angle, and for C you will substitute the hypotenuse (longest line, slanted.)
once you do that, you take the two numbers you do have and simplify (get rid of the ².) then you use the 2 numbers to find the third.
this means you either
add the A and B together
A= 3²
B= 4²
C=?
3²+4²=C²
3² is 9
4² is 16
9+16=C²
25=C²
simplify
5=C
or you minus C by the number you do have.
A= 3²
B=?
C= 5²
3²+B²=4²
3² is 9
5² is 25
9+B²=25
minus both the 25 and the 9 by 9 to get rid of it.
9-9=0
25-9=16
this gets rid of the 9 on the left side by turning it into a 0.
that leaves
B²=16
you can either simplify further from here or leave it, depending on if the square root of C is a simple number.
in the case of 16, the square root is 4, which ends with no repeating decimals, so you should simplify.
something you should simplify
16² because it equals a simple number.
something you shouldn't.
13² because it equals an ongoing decimal.
(bottom)
if you still need help and can't do it yourself, or if you don't want to do it, then comment, I can continue to help. I just need to know if it's a right triangle or not. the way I solve the question depends on the type of triangle it is.
