Question 149196
In any given problem there's always an {{{unknown}}}????
Simply refer this "unknown" data to the letter in the equation you're using.
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For instance you're looking for the hypotenuse of a right triangle with 2 other sides given. We all know in solving this we have to use Pythagorean Theorem and as it states there in equation, {{{(hypotenuse)^2 = (opposite)^2 + (adjacent)^2}}} right?
Now usually they assigned "letters" in reference to the data given, where we can say,
hypotenuse= "c"
opposite= "b"
adjacent= "a"
Well since we're looking for the hypotenuse, "c" that represent it is the subject of the equation ----> {{{c^2 = a^2 + b^2}}}
If the opposite  or adjacent side is unknown, we'll make "a" or "b" the subject of the equation ----> {{{b^2 = c^2 - a^2}}} or {{{a^2 = c^2 - b^2}}}
Hope this help.
<font><font size=4><b>Thank you,
Jojo</font>