Mensuration Chapter 11: Perimeter and Area of Plane Closed Figures

Area and Perimeter of Rectangular Shapes

• Area of a rectangular park with length 30m and width 20m is 30m x 20m = 600m²
• Perimeter of a rectangular park with length 30m and width 20m is 2(l + w) = 2(30 + 20) = 100m

Cementing a Path

• 1 bag of cement is required to cement 4m² area
• To construct a cemented path of 70m² area, 70m² / 4m² = 17.5 bags of cement would be required

Context of Cementing a Path

• If the area of the park is 30m x 20m, and the path is 1m wide, the total area of the path is 30m x 20m - 28m x 18m = 70m²
• To cement the path, 70m² / 4m² = 17.5 bags of cement would be required

Area and Perimeter of General Shapes

• Region covered by a closed plane figure is referred to as area
• Distance around the boundary of a closed plane figure is called perimeter

Area Covered by Grass in a Park

• If there are two rectangular flower beds of size 1.5m x 2m each, the total area of the flower beds is 2(1.5m x 2m) = 6m²
• Area covered by grass in the park is 30m x 20m - 6m² = 594m²

Comparison of Areas

• If a square and a rectangular field have the same perimeter, the square field has a larger area

Area of Parallelogram

• If a flooring tile has the shape of a parallelogram with a base of 24 cm and a height of 10 cm, the area of the tile is 24 cm x 10 cm = 240 sq.cm
• To cover a floor area of 1080 sq.cm, 1080 sq.cm / 240 sq.cm = 4.5 tiles are required

Shapes and Perimeter

• An ant has to take a longer round if it's moving around a circle-shaped food piece

Reproduction in Animals

• Reproduction is essential for the continuation of a species
• Two modes of reproduction are: sexual reproduction and asexual reproduction
• Example of a young one of an animal is a kitten

Importance of Reproduction

• Reproduction is important for every individual to ensure the continuation of the species
• Purpose of learning about reproduction in animals is to understand the life cycle of species

Consequences of No Reproduction

• If organisms had not reproduced, species would have become extinct

Types of Reproduction

• Two types of reproduction mentioned in the text are: sexual reproduction and asexual reproduction

Reproductive Parts in Plants and Animals

• Male reproductive parts in plants and animals are called gametes
• Purpose of the tail in a sperm is to aid movement
• Female reproductive organs in humans are ovaries, oviduct, and uterus
• One ovary releases an egg into the oviduct every month in human females

Process of Reproduction

• First step in the process of reproduction is the fusion of nuclei of sperm and egg
• Result of the fusion of the nuclei of the sperm and the egg is a zygote
• Largest egg mentioned in the text is that of an ostrich

Fertilization

• During fertilization, the sperm fuses with the egg
• A zygote is the result of fertilization