You are going to learn about the chapter called surface area, this topic is taken from the class 9th it mostly explains the surface of a product and their shapes. From this topic mostly they ask for the competitive exams. Here we are going to know what they are.
Text contents only for the surface area
- Surface area of a cuboid and a cube
- Surface area of a right circular
- Surface area of a right circular cone
Surface area of a cuboid and a cube
If the cuboid has length l, breadth b, and height h,
Perimeter Of Cuboid = 4(l + b + h), the surface area of the cuboid = 2(lb+bh+lh),Lateral surface area of the cuboid = 2(l+b)xh, Volume of the Cuboid = lbh
If the length of each edge of a cube is l, then the perimeter of the cube=121=12 (edge)2, the surface area of the cube= 6 I2= (edge)2, Lateral surface area of the cube = 4l2 =4(edge)2.
Example for the understanding rest of the questions u will get in text
Q Find the lateral surface of an area and total surface area of the cuboid of length 80 cm, breadth 40 cm, and height 20 cm.
Solution:- Length of the cuboid (l) = 80 cm, Breadth (b) =40 cm, Hight (h)= 20 cm
i) ∴ Lateral surface of an area = 2h(l + b)
=2 x 20(80 + 40) cm² = 40 x 120 = 4800 cm²
(ii)The total surface area is = 2(lb+bh+hl)
= 2(80 x 40 + 40 x 20 + 20 x 80) cm² = 2(3200 + 800 + 1600) cm² = 5600 x 2 = 11200 cm²
Surface area of a right circular
Let us discuss the right circular cylinder properties. If the line joining to the center of the circle is called the axis. When we are revolvet a rectangle about one side then the axis of revolution takes place, then the right cylinder is formed.
The section is obtained on cutting a right circular cylinder by the plan, which contains two elements, and the parallels to the cylinder are known as a rectangle. Then if the plane cuts the right cylinder horizontally it is parallel to the bases, then it is called a circle
Example for the understanding rest of the questions u will get in text Q Find the volume of a right cylinder if the radius and the height of a cylinder are 20 cm and 30 cm respectively.
Solution: We know,
The volume of a right cylinder is = πr2 h cubic units
Given is the r = 20 cm h = 30 cm
Therefore, using the formula, we get;
Volume = 3.14 × 202 × 30
= 3.14 × 20 × 20 × 30
The volume of a given right cylinder is the = 37680 cm3
Surface area of a right circular cone
If the r, h, and l are denoted respectively to the radios of base, height, and slant height of a right circular cone, then:
These types of questions are asked in the exams. Make a practice of these questions. for the competitive exams, and after completing the task, now you have a deep knowledge surface area chapter to make showers fulfill your dreams.