Ex 9.2, 8 - Chapter 9 Class 7 Perimeter and Area
Last updated at April 16, 2024 by Teachoo
Chapter 9 Class 7 Perimeter and Area
Concept wise
- Basic Definitions
- Square and Rectangle
- Converting Square to Rectangle
- Area of parallelogram
- Area of triangle
- Circumference of circle
- Perimeter of a combination of shapes
-
Area of circle
- Area of combination of figures - two circles, circle and square
- Finding Area of rectangle with path outside/inside
- Finding Area of rectangle with cross roads
- Finding Area of rectangle with triangle
Transcript
Ex 9.2, 8 Find the cost of polishing a circular table-top of diameter 1.6 m, if the rate of polishing is Rs 15/m2. (Take Ο = 3.14) Here, Area to be polished = Area of circular table top Diameter = 1.6 m Radius = r = π·πππππ‘ππ/2 = (π.π)/π = 16/(2 Γ 10) Area of table top = πr2 = 3.14 Γ (π/ππ)^π = 314/100 Γ 8/10 Γ 8/10 = (πππ Γ ππ)/πππππ = 20096/10000 = 2.0096 m2 Now, Cost of polishing 1 m2 area = Rs 15 Cost of polishing 2.0096 m2 area = Rs 15 Γ 2.0096 = Rs 15 Γ πππππ/πππππ = Rs 3 Γ 20096/2000 = Rs 3 Γ πππππ/ππππ = Rs 30144/1000 = Rs 30.144 = Rs 30.14 (approx.) β΄ It will cost Rs 30.14 (approx.) to polish the table top
