• Support PF! Buy your school textbooks, materials and every day products Here!

Solving an equation involving sin and cos terms

  • Thread starter nokia8650
  • Start date
  • #1
219
0
Hi

I was wondering if there is a non-numericla way to solve the following equation:

144 - 90sin x - 155.8cos x = 0

Thanks
 

Answers and Replies

  • #2
HallsofIvy
Science Advisor
Homework Helper
41,833
955
Hi

I was wondering if there is a non-numericla way to solve the following equation:

144 - 90sin x - 155.8cos x = 0

Thanks
That's not a nice equation but here's what I might do: write it as 90 sin x= 144- 155.8 cos x
[itex]90\sqrt{1- cos^2 x}= 144- 155.8 cos x[/itex] and square both sides to get [itex]8100(1- cos^2 x)= 20736- 44870.4cos x+ 24273.64cos^2 x[/itex]. Solve that quadratic equation for cos x and then take the arccosine to find x. When you square both sides of an equation, that new equation may have roots that do not satisfy the original equation.
 
  • #3
219
0
Thank you!
 

Related Threads on Solving an equation involving sin and cos terms

Replies
5
Views
1K
Replies
3
Views
1K
Replies
5
Views
1K
Replies
1
Views
1K
  • Last Post
2
Replies
47
Views
3K
Replies
6
Views
2K
Replies
19
Views
992
  • Last Post
Replies
1
Views
2K
Replies
1
Views
2K
Top