Find the values of x for which the equation cos x = –1 is true. Let k represent an integer.

Question

jkasdhk · Answer

x = (cos)^-1 (-1)

anonymous · Answer

these are the answer choices
2pik
pi/2 + 2k
pi + 2pik
3pi/2+ 2pik

jkasdhk · Answer

isn't there k in the equation? which we're supposing as an integer?

anonymous · Answer

i have no idea. i don't even know where to begin :(

jkasdhk · Answer

hold on.. and check the question again if it is the same u've written?

anonymous · Answer

Find the values of x for which the equation cos x = –1 is true. Let k represent an integer.

jkasdhk · Answer

I'm gonna go now, will tell u after solving..

anonymous · Answer

thanks

jkasdhk · Answer

Well when is cosx = -1 the first time in the circle?

At π (because x=180 degrees)... right?

So now when does it occur again, well it doesnt happen again until we go around in a full circle.
So another 2π and this will happen indefinitely for any integer k.

So the answer is:
π + 2πk