Introduction to Trigonometry Exercise 8.2

NCERT solutions for Maths Introduction to Trigonometry 

NCERT Solutions for Class 10 Maths Introduction to Trigonometry

1. Evaluate:

(i)

(ii)

(iii)

(iv)

(v)

Ans. (i)

=

= =1

(ii)

=

= =2

(iii)

= =

= =

=

= =

=

(iv)

= = =

=

= =

(v)

=

=

= =

NCERT Solutions for Class 10 Maths Exercise 8.2

2. Choose the correct option and justify:

(i) =

(A)

(B)

(C)

(D)

(ii) =

(A)

(B) 1

(C)

(D) 0

(iii) is true when A =

(A)

(B)

(C)

(D)

(iv) =

(A)

(B)

(C)

(D) Non e of these

Ans. (i) (A)

=

= = =

(ii) (D) = = = 0

(iii) (A) Since A = 0, then

and

=

when A = 0

(iv) (C)

= =

= =

NCERT Solutions for Class 10 Maths Exercise 8.2

3. If and find A and B.

Ans.

A + B = ……….(i)

A – B = ……….(ii)

On adding eq. (i) and (ii), we get,

2A = A =

On Subtracting eq. (i) and eq. (ii), we get

2B = B =

NCERT Solutions for Class 10 Maths Exercise 8.2

4. State whether the following are true or false. Justify your answer.

(i)

(ii) The value of increases as increases.

(iii) The value of increases as increases.

(iv) for all values of

(v) is not defined for

Ans. (i) False, because

= 1

And =

(ii) True, because

It is clear, the value of increases as increases.

(iii) False, because

It is clear, the value of decreases as increases

(iv) False as it is only true for

(v) True, because and

= i.e. undefined.