## ParthKohli one year ago I will state the question exactly as it is:

1. ParthKohli

If $$x,y \in [0, \pi/2)$$:$\sin^4 x + \cos^4 y + 2 = 4\sin x \cos y$Then find the value of:$\sin x + \sin y$... The answer is given as 2.

2. anonymous

@Mehek14 @pinkbubbles

3. ParthKohli

I have two issues with this: one, $$\pi/2$$ is not included. If I acknowledge this as a small mistake, even then, if $$\sin x + \sin y = 2$$, then $$x = y = \pi/2$$. But of course this does not satisfy the condition. Here is what *does* satisfy the condition: $$x = 0;~ y = \pi/2$$

4. ParthKohli

@ganeshie8

5. ParthKohli

@ikram002p @dan815

6. anonymous

@SolomonZelman

7. ParthKohli

@oldrin.bataku of course.

8. ParthKohli

Oops, I meant that $$y = 0; x = \pi/2$$ satisfies the condition. Moving on...

9. imqwerty

Pi/2 MUST be included.

10. imqwerty

I've solved the question thoroughly nd m sure that pi/2 mst be included.

11. ParthKohli

Even then, the answer couldn't be 2, right?

12. ParthKohli

Also, how did you solve this question thoroughly if you don't mind explaining?

13. imqwerty

K wait lemme switch on my laptop :)

14. ParthKohli

Did you solve this my maxima-minima or ...?

15. imqwerty

No i jst simplified the expression

16. ParthKohli

Oh, great.

17. imqwerty

18. ParthKohli

Yeah, that's what I got too... finally.

19. ParthKohli

Thank you!

20. ParthKohli

So the answer isn't 2, it's 1, right?

21. ParthKohli

The question asked for sin x + sin y...

22. imqwerty

yes its one :)

23. ParthKohli

Cool, I was wondering where the mistake was in my work. There wasn't any. I'll report this, thanks!

24. imqwerty

ur welcome :)