In this item, it is assumed that since the pattern is cut out of the paper which is usually a rectangle then, the shape of the pattern is also rectangle. The perimeter of the rectangle is,
P = 2L + 2W
The area is equal to,
Area = L x W
If we assume that length and width are equal, in order to maximize the space.
1600 cm² = L x L
The value of L from the equation is 40 cm.
A^2 + B^2=C^2 so there for the hypotenuse (13^2) - (5^2) will give you the last side
32 degees, 43.8 degrees, 53.8, 63.8 Yes they are proportional