CBSE Class 10 Maths Chapter-6 Triangles – Free PDF Download
Free PDF download of Important Questions with Answers for CBSE Class 10 Maths Chapter 6 – Triangles prepared by expert Maths teachers from latest edition of CBSE(NCERT) books only by CoolGyan to score more marks in CBSE board examination.
CBSE Class 10 Maths Chapter-6 Triangles Important Questions
CBSE Class 10 Maths Important Questions Chapter 6 – Triangles
4 Mark Questions
1. Prove that if a line is drawn parallel to one side of a triangle to intersect the other two sides in district points, ten other two sides are divided in the same ratio. By using this theorem, prove that in 
if 
then 
Ans. Given: In 
intersect AB at D and AC at E.
To Prove: 
Construction: Draw 
and 
and join DC and BE.
Proof: 
Similarly,
Since 
and 
are on the same base and between the same parallels
2. Prove that the ratio of areas of two similar triangles are in the ratio of the squares of the corresponding sides. By using the above theorem solve in two similar triangles PQR and LMN, QR = 15cm and MN = 10 cm. Find the ratio of areas of two triangles.
Ans. Given: Two triangles ABC and DEF
Such that 
To Prove: 
Construction: Draw 
and 
Proof: 
Again, in 
and 
we have
[By AA rule]
[
Corresponding sides of similar triangles are proportional]
Further,
From (ii) and (iii),
Putting in (i), we get
Hence,
Since 
Hence, required ratio is 9:4.
3. Prove that in a right-angled triangle the square of the hypotenuse is equal to the sum of the squares of the other two sides.Use the above theorem in the given figure to prove that
Ans. Given: right-angled at A
To Prove: 
Construction: Draw 
from A to BC
Proof: In 
[Common]
[By AA similarity]
Similarly, in 
and 
[Common]
[By AA similarity]
To Prove: 
Proof: In 
[Using above theorem]
4. Prove that the ratio of areas of two similar triangles is equal to the square of their corresponding sides.Using the above theorem do the following the area of two similar triangles are 
and 
, if the largest side of the smaller triangle is 27 cm, then find the largest side of the largest triangle.
Ans. Given: Two triangles ABC and DEF such that
To prove:
Construction: Draw and
Proof: Since similar triangles are equiangular and their corresponding sides are proportional
And 
In and 
[By AA similarity]
From (i) and (ii), we get
Now 
Hence,
Let the largest side of the largest triangle be 
cm
Using above theorem,
5. In a triangle if the square of one side is equal to the sum of the squares on the other two sides. Prove that the angle apposite to the first side is a right angle.Use the above theorem to find the measure of 
in figure given below.
Ans. Given: A such that
To prove: Triangle ABC is right angled at B
Construction: Construct a triangle DEF such that
andÐ
Proof: 
is a right angled triangle right angled at E [construction]
By Pythagoras theorem, we have
Thus, in and 
we have
[By Construction and (i)]
Hence,is a right triangle.
In 
Now in 
is right angled at K
