Find the solution:
7 cos^-1 x - π = 5 cos^-1 x

Question

Find the solution:
7 cos^-1 x - π = 5 cos^-1 x

anonymous · Answer

7/(cosx) - Pi = 5/(cosx) >> [7/(cosx)] - [5/(cosx)] = Pi >> 2/(cosx) = Pi >> 2 = cos (Pix)  >> cosx = 2/Pi

anonymous · Answer

If you substitute 2/Pi in the place of cosx you should get the same answer for both sides

anonymous · Answer

Idk if this helps, but the answer is {0}

anonymous · Answer

What are you looking for? cosx ?

anonymous · Answer

Let me write it down, hold on a sec o:

anonymous · Answer

I'm a bit confused by you "/", are they division signs? o:

anonymous · Answer

yes, they mean division. To be honest I'm not sure how the answer comes out to be zero, this seemed like the logical answer to me. Sorry :(

anonymous · Answer

is the -Pi in the denominator ?

anonymous · Answer

But why were you dividing from the beginning? o:

chillout · Answer

I guess (s)he though that it was cos^-1 instead of arccos. Well, Going to try to solve it.

chillout · Answer

By the way, on the left side of the equation is it cos^-1(x-π) or cos^-1(x) - π?

anonymous · Answer

All she gave me was 7 cos^-1 x -π, so I suppose the second one

hartnn · Answer

yes, it must be $7 cos^{-1} x - π = 5 cos^{-1} x$
Also, $cos^{-1} x \ne 1/ \cos x$
its inverse cos function, or called 'arccos x'
so, lets first try to isolate $cos^{-1} x$
can you ?

anonymous · Answer

cox^-1 x=π/2, right?

hartnn · Answer

correct!
now $if, cos^{-1} a=b, \implies a=\cos b$
so, 
$cos^{-1} x=\pi/2 \implies x = \cos (\pi/2)=..?$

anonymous · Answer

x? o:

hartnn · Answer

finding solution means finding 'x' 
so, yes 'x'
do you know cos (pi/2) =... ?

anonymous · Answer

0 OMG THANK YOU.

hartnn · Answer

yes, x=0
welcome ^_^