it is of 7th class question (CBSE) chapter:Perimeter and area.
Answers
Answer:
60cm² & 72cm²
Step-by-step explanation:
A) Since it a rectangle of sides 12cm and 10cm, the area of total shape is 120cm² [area = length * breadth]
Now the area of the triangle in white = 1/2 * b * h[General formula]
= 0.5 * 10 * 12
= 60cm²
Area of the shaded region = Area of rectangle - Area of the white portion
= 120 cm² - 60cm²
= 60cm²
B) Since it a rectangle of sides 12cm and 15cm, the area of total shape is 180cm² [area = length * breadth]
Now, the area of ΔDPE = 1/2 * b * h[General formula]
= 0.5 * 9 * 6 [PE=EO = PO/2]
= 27cm²
Similarly , the area of ΔDMN = 1/2 * b * h[General formula]
= 0.5 * 12 * 6 [DM = MP-DP]
= 36cm²
Similarly , the area of ΔNOE = 1/2 * b * h[General formula]
= 0.5 * 15 * 6 [DM = MP-DP]
= 45cm²
Area of the shaded region = Area of rectangle - (ar[ΔDPE]+ ar[ΔDMN] + ar[ΔNOE])
= 180 cm² - (27+36+45)cm²
= 72cm²