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Mathematics 18 Online
OpenStudy (adi3):

Please help will medal http://prntscr.com/anzdnc

imqwerty (imqwerty):

do you know the general formula for \(tan\) and \(sin\) ?

OpenStudy (adi3):

yes

imqwerty (imqwerty):

okay we simplify the 1st one-> \(tan^2 x+tanx=0\) \(tanx(tanx+1)=0\) so either \(tanx=0\) or \(tanx+1=0\) -> \(tanx=-1\) now try finding the solutions

OpenStudy (adi3):

y is it tanx+1?

OpenStudy (adi3):

i dont get this

OpenStudy (adi3):

@phi

OpenStudy (phi):

forget about tan for the moment if you had y^2 + y= 0 or , after "factoring out" they y: y(y+1) = 0 you have two terms: y and (y+1) if you multiply two things and get 0 then you say: one of them (or maybe both!) must be 0 for example, if y=0 you would have 0 * (0+1) = 0*1 and that is zero or if y=-1, you would have -1* (-1+1) = -1* 0 and that is zero

OpenStudy (adi3):

you are beast

OpenStudy (phi):

use that idea for your problem \[ \tan^2 x + \tan x = 0 \]

OpenStudy (adi3):

so if we factor tan x then this is equal to what @imqwerty said right?

OpenStudy (adi3):

tanx(tanx+1)=0

OpenStudy (phi):

yes, and to get 0 , one or the other of the terms must be zero so one solution is tan x = 0 and the other solution is tan x + 1 = 0

OpenStudy (adi3):

ok, what about the second one?

OpenStudy (phi):

they restrict the answer to be between -pi/2 and pi/2 (-90 deg and + 90 degrees) tan x + 1 = 0 add -1 to both sides, and simplify: tan x + 1 - 1= 0 -1 tan x = -1 you should know what angle "x" is (you memorized sin, cos, tan values for 0, 30, 45, 60 and 90 degrees, right?)

OpenStudy (phi):

or you know tan A = y/x |dw:1459774686856:dw|

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