Shannon has a square piece of paper NPQR of side 70 cm. She cut along the dotted lines shown in Figure 1 to get one small square of area 100 cm
2 and 8 identical right-angled triangles. Triangle STU in Figure 2 is one such triangle. Find the length of SU.
Area of the square piece of paper
= 70 x 70
= 4900 cm
2 Area of 8 triangles
= 4900 - 100
= 4800 cm
2Area of 4 outer triangles
= 4800 ÷ 2
= 2400 cm
2 Area of the inner dotted-line square
= 4900 - 2400
= 2500 cm
2 Length of inner dotted-line square
= √2500
= 50 cm
Length of SU = 50 cm
Answer(s): 50 cm