4 identical triangles are cut off from the 4 corners of a square of side 20cm as shown . by how much did the perimeter decrease.
Perimeter of square = 4s
= 4 * 20
= 80 cm
Reduced side of triangle = 4(4 + 3)
= 4*7
= 28
Increased side of triangle = 4 * 4 + 3 * 3
= 16 + 9
= under root 25
= 5 cm
5 * 4 = 20 cm
28-20 = 8 cm
Therefore, the perimeter decreased by 8 cm.
= 4 * 20
= 80 cm
Reduced side of triangle = 4(4 + 3)
= 4*7
= 28
Increased side of triangle = 4 * 4 + 3 * 3
= 16 + 9
= under root 25
= 5 cm
5 * 4 = 20 cm
28-20 = 8 cm
Therefore, the perimeter decreased by 8 cm.