RBSE Solutions for Class 9 Maths Chapter 11 Area of Plane Figures Ex 11.1

RBSE Solutions for Class 9 Maths Chapter 11 Area of Plane Figures Ex 11.1 is part of RBSE Solutions for Class 9 Maths. Here we have given Rajasthan Board RBSE Class 9 Maths Solutions Chapter 11 Area of Plane Figures Exercise 11.1.

 Board RBSE Textbook SIERT, Rajasthan Class Class 9 Subject Maths Chapter Chapter 11 Chapter Name Area of Plane Figures Exercise Ex 11.1 Number of Questions Solved 7 Category RBSE Solutions

Rajasthan Board RBSE Class 9 Maths Solutions Chapter 11 Area of Plane Figures Ex 11.1

Question 1.
The base and height of a triangle are 20 cm and 6 cm. Find the (RBSESolutions.com) area of the triangle.
Solution.
Area of triangle = $$\frac { 1 }{ 2 }$$ × base × altitude
= $$\frac { 1 }{ 2 }$$ × 20 × 6 = 60 cm²

Question 2.
Find the area of the triangle whose sides are 15 cm, 25 cm and 30 cm respectively.
Solution.
Let a = 15 cm, b = 25 cm and c = 30 cm

Question 3.
Find the area of an isosceles triangle, the measure (RBSESolutions.com) of one of its equal sides being 8 cm and the third side is 4 cm.
Solution.
Area of an isosceles triangle

Question 4.
Find the area of an equilateral (RBSESolutions.com) triangle whose side is 20 cm.
Solution.
Area of an equilateral triangle

= 100√3 sq. cm.

Question 5.
A triangular plot whose two sides are 8 cm and 15 cm and its perimeter is 40 cm, then find the area of the triangular plot.
Solution.
Perimeter of triangular plot = sum of all the three sides
40 = 8 + 15 + third side
=> Third side = 40 – 23 = 17 cm
Area of triangular plot

Question 6.
A triangular table whose sides are in the ratio 3:4:5 and (RBSESolutions.com) its perimeter is 36 m, then find the area of triangular table.
Solution.
Sides of table are given as 3 : 4 : 5
i.e. sides are 3x, 4x and 5x
∴Perimeter = 36 m
i.e. 3x + 4x + 5x = 36
⇒ 12x = 36
⇒ x = 3
∴Sides are 3x = 3 x 3 = 9 m
4x = 4 x 3 = 12 m
5x = 5 x 3 = 15 m
Area of triangular table

Question 7.
The sides of a triangular field are 20 m, 51 m and 37 m. Find the (RBSESolutions.com) number of flowerbeds that can be prepared if each bed is to contain 2 x 3 sq. metre space.
Solution.
Let sides of a triangular field be
a = 20 m, 6 = 51 m and c = 37 m

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