9
.
perfect square:
square
units
square root:

examples:  

Perfect square- 9 multiplied by 9 is a perfect square because it = 81

(two same numbers multiplied together create a perfect square)

square units- on grid paper how many squares would be filled to creat 9 multiplied by 9

square roots-  √81 ()using this symbol divide 81 into 2 and if the number you get is even then it is a perfect square

56.6

step-by-step explanation:

the ratio of the perimeters is equal to the scale.

the ratio of the areas is equal to the square of the scale.

34 / 20 = k

a / 19.6 = k²

substituting:

a / 19.6 = (34 / 20)²

a = 19.6 (34 / 20)²

a ≈ 56.6