RD Sharma Chapter 18 Class 9 Maths Exercise 18.1 Solutions basically covers questions around the surface area and Cuboid volumes. Upon practicing these exercises, a student can learn about the Cuboid surface area and the surface area of cubes. However, before delving into the exercises, the students need to possess significant concepts in the concerned subject. Not just for the exercise, this can be useful for future studies as well, or those who are aspiring for higher studies in Mathematics.

The best part about the RD Sharma Chapter 18 Class 9 Maths Exercise 18.1 Solutions is that these have been provided most engagingly and intuitively for the students, making things interesting for them to study Mathematics.

**Learn about RD Sharma Class 9 Chapter 18 (Surface Area And Volume of A Cuboid And Cube)**

Table of Contents

## Download RD Sharma Chapter 18 Class 9 Maths Exercise 18.1 Solutions PDF

Solutions for Class 9 Maths Chapter 18 Surface Area and Volume of Cuboid and Cube Exercise 18.1

## Important Definitions RD Sharma Chapter 18 Class 9 Maths Exercise 18.1 Solutions

In this exercise of Chapter 18, we will discuss the following topics with the definitions and stepwise examples-

- Surface Area of a Cuboid
- Surface Area of a Cube
- Lateral Surface Area of a Cuboid
- Lateral Surface Area of a Cube

### Surface Area of a Cuboid

Cuboid comes with six rectangular faces, the surface area of which is calculated upon adding the areas of all six faces. It can also be calculated applying the formula SA= 2lw+2lh+2hw, where l means length, w means width, and h means the height of the prism.

### Surface Area of a Cube

The surface area of a cube is calculated through formula A=6a2, where A is the area, and a is the length of the edge.

### Lateral Surface Area of a Cuboid

The lateral surface area of Cuboid has calculated through the formula Lateral Surface area = 2 height (length + breadth)

### Lateral Surface Area of a Cube

The lateral surface area of the cuboid is calculated through formula 4a2, where a is the length of each side.

### Examples of RD Sharma Chapter 18 Class 9 Maths Exercise 18.1 Solutions

**Ques:** **Find the lateral surface area and total surface area of a cuboid of length 80cm, breadth 40cm, and height 20cm.**

**Solution-**

Dimensions of the cuboid:

Length (L) = 80 cm

Breadth (B) = 40 cm

Height (H) = 20 cm

Total Surface Area = 2[LB + BH + HL]

By equating the values

= 2[(80)(40)+(40)(20)+(20)(80)]

= 2[3200+800+1600]

= 2[5600]

= 11200

Therefore, Total Surface Area = 11200 cm2

Lateral Surface Area = 2[L + B]H

= 2[80+40]20

= 40[120]

= 4800

So the Lateral Surface Area is 4800 cm2.

**Ques: Find the lateral surface area and total surface area of a cube of edge 10 cm.**

**Solution:**

Side of the Cube = 10 cm (provided)

Lateral Surface Area of cube = 4 side2

Cube Lateral Surface Area = 4(10 x 10)

= 400cm2

Total Surface Area = 6 Side2

= 6(102)

= 600cm2

**Ques: Find the ratio of the total surface area and lateral surface area of a cube.**

**Solution:**

Total Surface Area (TSA) = 6 Side2

Lateral surface area (LSA) = 4 Side2

Ratio of TSA and LSA of the cube = (6 Side2)/ (4 Side2) = 3/2 or 3:2.