The area of the green square is 9 ft2. the area of the red square is 16 ft2. whats the length of side c ?
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To do this, divide the total square footage by its square root. The square root of 9 is 3. 9 divided by 3 is 3. All sides of the green square are 3 ft in length. The square root of 16 is 4. 16 divided by 4 is 4. All the sides of the red square are 4 ft in length.

Angle = tan(opposite/adjacent)

arctan Angle = arctan(34/122)

angle = 15.57