Thank you for registering.

One of our academic counsellors will contact you within 1 working day.

Please check your email for login details.

Use Coupon: CART20 and get 20% off on all online Study Material

Total Price: Rs.

There are no items in this cart.
Continue Shopping

Period of f(x)=sin 4 x + cos 4 x is ??? How???

Period of f(x)=sin4x + cos4x is ??? How???

Grade:12th Pass

2 Answers

Swapnil Saxena
102 Points
9 years ago

Differentiate the function with respect to x.

d/dx of sin^4(x)+cox^4(x)=4sin^3(x)cos(x)-4cos^(x)sin(x)

Putting it equal to 0.



sin(x)cos(x)=0 or sin^2(x)-cos^2(x)=0

If sin(x)=0,x=0 or cos(x)=0,x=(pie/2) (MAXIMA OF THE FUNCTION)

If sin^2(x)-cos^2(x)=0 then sin^2(x)=cos^2(x) or x=(pie)/4 or x=3(pie)/4 (MINIMA OF THE FUNCTION)

Since the function  has the same value after an interval of pie/2, So the period must be (pie)/2.

Ashwin Muralidharan IIT Madras
290 Points
9 years ago

Hi Aditi,


As powers of sin and cos are even, and we have the sum of both sin and cos, they both can interchange and add.

ie A+B is same as B+A.


So period of the above function will be pi/2.


Best Regards,

Ashwin (IIT Madras).

Think You Can Provide A Better Answer ?

Provide a better Answer & Earn Cool Goodies See our forum point policy


Get your questions answered by the expert for free