CBSE Class 10 Maths Chapter-8 Introduction to Trigonometry – Free PDF Download
Free PDF download of Important Questions with Answers for CBSE Class 10 Maths Chapter 8 – Introduction to Trigonometry 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-8 Introduction to Trigonometry Important Questions
CBSE Class 10 Maths Important Questions Chapter 8 – Introduction to Trigonometry
3 Mark Questions
1. Given 
calculate all other trigonometric ratios.
Ans. Consider a triangle ABC in which 
A = 
and B = 
Let AB = 
and BC = 
Then, using Pythagoras theorem,
BC = 
= 
= 
= 
=
2. If 
evaluate:
(i) 
(ii) 
Ans. Consider a triangle ABC in which A = and B =
Let AB = 
and BC = 
Then, using Pythagoras theorem,
AC = 
= 
= 
= 
= 
(i)
= 
= 
= 
= 
(ii) 
= 
=
3. If 
check whether 
or not.
Ans. Consider a triangle ABC in which B = .
And 
Let AB = 
and BC = 
Then, using Pythagoras theorem,
AC =
= 
= 
= =
And 
Now, L.H.S. 
= 
= 
= 
R.H.S. 
= 
= 
=
L.H.S. = R.H.S.
=
4. In 
ABC right angles at B, if 
find value of:
(i) 
(ii) 
Ans. Consider a triangle ABC in which B = .
Let BC = 
and AB = 
Then, using Pythagoras theorem,
AC =
= 
= 
= 
= 
For C, Base = BC, Perpendicular = AB and Hypotenuse = AC
(i)
= 
= 
= 1
(ii)
= 
= 
5. In PQR, right angled at Q, PR + QR = 25 cm and PQ = 5 cm. Determine the values of 
and 
Ans. In PQR, right angled at Q.
PR + QR = 25 cm and PQ = 5 cm
Let QR = 
cm and PR = 
cm
Using Pythagoras theorem,
RP2 = RQ2 + QP2
RQ = 12 cm and RP = 25 – 12 = 13 cm
And 
6. If 
and 
find A and B.
Ans. (i) False, because 
= 1
And 
= 
(ii) True, because
|  |  |  |  | |
 | 0 |  |  |  | 1 |
It is clear, the value of increases as increases.
(iii) False, because
| | | | | |
 | 1 | | | | 0 |
It is clear, the value of decreases as increases
(iv) False as it is only true for 
True, because 
and 
= 
i.e. undefined
7. Choose the correct option. Justify your choice:
(i) 
=
(A) 1 (B) 9 (C) 8 (D) 0
(ii) 
=
(A) 0 (B) 1 (C) 2 (D) none of these
(iii) 
=
(A) 
(B) 
(C) 
(D) 
(iv) 
=
(A) 
(B) 
(C) 
(D) none of these
Ans. (i) (B) = 
= 9 x 1 = 9
(ii) (C)
= 
= 
= 
= 
= 
= 
= 2
(iii) (D)
= 
= 
= 
= 
=
(iv) (D) = 
= 
= 
= 
= 
