Please help asap. im not sure what the answer is

85cm² (this might be wrong)

Step-by-step explanation:

Perimeter = 4a

(a) is a side

40/4 = 10

10-7=3

Pythagorean theorem:

C² = A² + B²

3²+10²=109

√109

4²+10²=116

116+109=225

√225=15

Square are = a²

10²=100

100-15=85

9514 1404 393

  55%

Step-by-step explanation:

If the perimeter of the square is 40 cm, the length of each side is 1/4(40 cm) = 10 cm.

If we draw a diagonal through the shaded area, it divides the triangle into two parts. One has a base of 7 cm and a height of 10 cm; the other has a base of 4 cm and a height of 10 cm. The total area of those two triangles is the shaded area.

The area of a triangle is given by the formula ...

  A = 1/2bh

Then the two triangles' area is ...

  A = 1/2(7 cm)(10 cm) +1/2(4 cm)(10 cm) = (7 +4 cm)(5 cm) = 55 cm^2

The area of the square is the square of its side length:

  A = (10 cm)^2 = 100 cm^2

Then the percentage of area that is shaded is ...

  shaded fraction = (shaded area)/(total area)

  shaded fraction = (55 cm^2)/(100 cm^2) × 100% = 55%