When two straight lines cross, it is found that the angles opposite to each ate the same size. They are known as

The angles don't need to be lined up vertically, or have one over top another. You could have them laid out horizontally. All that matters is that they are opposite angles after an X shape has been formed by two crossing lines. Vertical angles are always congruent.

since your problem is x^4 = 81, what you have to undeo is the "to the fourth power" part.

the inverse (opposite operation) of "to the fourth power" is "to the fourth root".

  (x^4) ^ ¼   = 81 ^ ¼  

  81 = 3^4     so (3 ^ 4) ^ ¼   =   3 ^ 1   = 3

by hand: (3 ^ 4) ^ ¼   =   3 ^ (4 x ¼) = 3 ^ 1   = 3   (when you take a power to a power, multiply the exponents.)

or, do it by calculator. one way of finding the fourth root is to use ^ (1/4)

step-by-step explanation:

because they could drop even lower..