Question

Solve the questions on the attached photo:

Answer 1

• See below

Explanation:

The easier way is to subtract areas.

Find the area of surrounding sections and the full rectangle and then subtract.

a)

Area of rectangle:

• 6*5 = 30 cm²

Area of triangles:

• 1/2(2*5 + 2*4 + 3*6) = 18 cm²

Area of the blue triangle:

• 30 - 18 = 12 cm²

b)

Area of rectangle:

• 6*5 = 30 cm²

Area of the four triangles:

• 1/2(2*4 + 2*3 + 5*3 + 2*1) = 15.5 cm²

Area of the blue quadrilateral:

• 30 - 15.5 = 14.5 cm²

c)

Area of rectangle:

• 7*5 = 35 cm²

Area of two trapezoids and 3 triangles:

• 1/2[(1 + 2)*1 + (3 + 4)*1 + 1*3 + 5*3 + 7*2] = 21 cm²

Area of the blue figure:

• 35 - 21 = 14 cm²

d)

Area of rectangle:

• 5*7 = 35 cm²

Area of three triangles and one trapezoid:

• 1/2[1*5 + 1*4 + 7*3 + (6 + 4)*2] = 25 cm²

Area of the blue figure:

• 35 - 25 = 10 cm²