70.80
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Polygons are similar when they have the same number of sides,
their corresponding angles are equal, and their corresponding
sides are all in the same ratio.
When that ratio is ' 1 ', they are also congruent.
That can happen sometimes, but it doesn't always have to happen.
Cos(angle) look at the 'x' axis, so cos(t)>0, means positive x, or quadrants I and IV.
tan(angle) = sin(angle)/cos(angle), so it's a division. sin(angle) has the sign of the y axis.
So, tan(t)>0, mus be +/+ or -/-, quadrant I or III, respectively.
The only in common is quadrant I. Hope it helps for the next one!
If I understood coorectly, you're looking for the fourth root of 81. This exercise can be solved by remembering that extracting the fourth root of a number is the same as raising that number to the power of 1/4.
We also need the prime factorization of 81, which is
So, the fourth root of 81 is 81 raised to the power of 1/4, which means
![\sqrt[4]{81} = \sqrt[4]{3^4} = (3^4)^{\frac{1}{4}}](https://tex.z-dn.net/?f=%20%5Csqrt%5B4%5D%7B81%7D%20%3D%20%5Csqrt%5B4%5D%7B3%5E4%7D%20%3D%20%283%5E4%29%5E%7B%5Cfrac%7B1%7D%7B4%7D%7D%20)
Now, use the property of exponents 
to convert the expression into
