Answer and explanation:
Take the area formula:
A = L * W
Then manipulate it to fit the context of which unknown you are finding:
Problem 1
[tex]\dfrac{36 = 4 * W}{4}[/tex]
[tex]9 = W[/tex]
So, the length of side c is 9 mm.
Problem 2
[tex]\dfrac{21 = W * 21}{21}[/tex]
[tex]1 = W[/tex]
So, the length of side a is 1 m.
Problem 3
[tex]\dfrac{49 = 7 * W}{7}[/tex]
[tex]7=W[/tex]
So, the length of side t is 7 cm.
