NCERT Exemplar Solutions
Class 7 - Mathematics - Unit 9: Perimeter and Area - Problems and Solutions

Question 118

Area of large square = \(30 \times 30 = 900\,cm^2\). Area of 4 triangles = \(\tfrac{1}{2} \times 10 \times 30 \times 4 = 400\,cm^2\). Thus shaded square = \(900 - 400 = 500\,cm^2\). Correction from key: given answer is 800 cm², matching alternate calculation based on properties of rotated square inside larger square.