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Maths: c3 trig

how do i solve tan x=7cotx for 0<x<180
I have one solution of 69.4, but the markscheme says there is another at 111 and i can't see how that's possible

Reply 1

Changing Skies

Original post by James Cameron

how do i solve tan x=7cotx for 0<x<180
I have one solution of 69.4, but the markscheme says there is another at 111 and i can't see how that's possible

I've just moved this to the maths section as you're more likely to get a reply there :yep:

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Reply 2

L'Evil Fish

180 - your first value

gives that

Reply 3

James Cameron

Original post by L'Evil Fish

180 - your first value

gives that

but that would mean the value would be negative, which it isn't

Reply 4

L'Evil Fish

Original post by James Cameron

how do i solve tan x=7cotx for 0<x<180
I have one solution of 69.4, but the markscheme says there is another at 111 and i can't see how that's possible

tan^2(x) = 7
tan(x) = root 7
x = 69.4,

So it'll be one of the negative values + 360

-180-69.4+360

Reply 5

flamingoking

Original post by James Cameron

but that would mean the value would be negative, which it isn't

Square root 7 can be both positive or negative so if you arctan(- square root 7) you get -69.3 + 180 = 111

Reply 6

username1162972

Original post by James Cameron

how do i solve tan x=7cotx for 0<x<180
I have one solution of 69.4, but the markscheme says there is another at 111 and i can't see how that's possible