Maths Help (1 Viewer)

Joined
May 22, 2021
Messages
98
Gender
Male
HSC
2022
3sinx = cosx

How do I solve this equation?I know it may seem easy but I forgot. Please help me thank you :)
 

Trebla

Administrator
Administrator
Joined
Feb 16, 2005
Messages
8,113
Gender
Male
HSC
2006
Moved to Maths Ext1 thread.

For future reference, please post these questions in the Maths forum.
 

pikachu975

Premium Member
Joined
May 31, 2015
Messages
2,739
Location
NSW
Gender
Male
HSC
2017
3sinx = cosx

How do I solve this equation?I know it may seem easy but I forgot. Please help me thank you :)
Minus cosx to both sides, so sqrt3 sinx - cosx = 0
cosx (sqrt3 tanx - 1) = 0
cosx = 0 and tanx = 1/sqrt3
cosx = 0 isn't valid since tan(pi/2) doesn't exist so only tanx = 1/sqrt3 is a solution
x = pi/6 then the other solutions depend on the domain of x

In this case dividing by cosx on both sides would give the right answer but in other questions it might remove a solution so be careful
 

idkkdi

Well-Known Member
Joined
Aug 2, 2019
Messages
2,454
Gender
Male
HSC
2021
Minus cosx to both sides, so sqrt3 sinx - cosx = 0
cosx (sqrt3 tanx - 1) = 0
cosx = 0 and tanx = 1/sqrt3
cosx = 0 isn't valid since tan(pi/2) doesn't exist so only tanx = 1/sqrt3 is a solution
x = pi/6 then the other solutions depend on the domain of x

In this case dividing by cosx on both sides would give the right answer but in other questions it might remove a solution so be careful
ye check scenario where the thing u divide by = 0 , in case that is a possible solution.
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top