Flag Trigonometry> Find the no. of solution of given trigono...
question mark

Find the no. of solution of given trigonometric equation where 0≤x≤5π(3+cosx)^2 = 4- 2sin^8x

Abha , 6 Years ago
Grade 12th pass
anser 2 Answers
Susmita

Last Activity: 6 Years ago

It is very easy to see that this equation will hold only for x=pi,x=3pi,x=5pi.
cospi=cos3pi=cos5pi=-1 and sin term will be zero.
(3-1)2=4
You can put these values and check.
So number of solution is 3.

Aditya Gupta

Last Activity: 6 Years ago

Let cosx=c and sinx be s
LHS is (3+c)^2, whose minimum value is 4
RHS is 4-2s^8 whose maximum value is 4.
So for them to be equal, both must equal 4.
So s=0 and c=-1
As c=-1 automatically implies s=0, hence we only need to focus on the solutions of cosx=-1=cosπ 
x= odd mutiple of pi
So x can be pi, 3pi, 5pi.
So there are exactly three solutions.

Provide a better Answer & Earn Cool Goodies

Enter text here...
star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments


Ask a Doubt

Get your questions answered by the expert for free

Enter text here...