Question

The complete solution of 7cos^2x + sinxcosx - 3 = 0 is ?​

Answer 1

Answer:

The given equation is equivalent to

7cos

2

x+sinxcosx−3(sin

2

x+cos

2

x)=0

or 3sin

2

x−sinxcosx−4cos

2

x=0

Since cosx=0 does not satisfy the given equation .

Divide throughout by cos

2

x we get

3tan

2

x−tanx−4=0

⇒(3tanx−4)(tanx+1)=0

⇒tanx=

3

4

or tanx=−1

x=kπ+tan

−1

3

4

or x=nπ+

4

3π

(n,k∈I)