
Keindrick W. answered 07/30/22
Experienced Math Tutor
Part A: The perimeter of a rectangle is P = 2L + 2W. L = 3k+1 W = k+3
P(rectangle) = 2(3k+1) + 2(k+3)
P(rectangle) = 6k + 2 + 2k + 6
P(rectangle) = 8k + 8
Since the perimeter of the rectangle is equal to the perimeter of the equilateral triangle, you must set them equal to each other.
8k + 8 = 4k - 4
Now solve for k.
1) Subtract 4k from both sides.
4k + 8 = - 4
2) Subtract 8 from both sides.
4k = -12
3) Divide 4 from both sides.
k = -3
Now we know that k = -3.
Part B: Area of the rectangle.
A = Length x width
We know what the length and width are. L = 3k + 1 W = k + 3
We know that k = -3 from Part A. Now we can find the length and width by substituting -3 in both equations for k.
L = 3(-3) + 1 = -8
W = -3 + 3 = 0
A = L x W
A = -8 x 0 = 0
Therefore, the area is 0.