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#1 2017-07-23 21:02:08

tyuighp
Member
Registered: 2015-12-04
Posts: 12

Find all angles θ

Find all angles θ in [0, 2π) for which
sin θ + cos θ + tan θ + cot θ + sec θ + csc θ = 6.4

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#2 2017-07-25 19:03:25

NakulG
Member
Registered: 2014-09-02
Posts: 186

Re: Find all angles θ

Sin2θ = -1, 0.96, 26

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#3 2017-07-25 19:07:28

bob bundy
Administrator
Registered: 2010-06-20
Posts: 8,137

Re: Find all angles θ

hi NakulG

I hadn't got anywhere with this.  Please would you give a few hints/.  Thanks smile

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#4 2017-07-25 19:53:03

NakulG
Member
Registered: 2014-09-02
Posts: 186

Re: Find all angles θ

sinθ + cos θ = x and sinθcosθ=y
substituting we get
x^3 - 6.4x^2+x+8.4=0
Solve for x, so x = -1, 1.4 & 6

Hope this helps...

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#5 2017-07-25 20:06:47

bob bundy
Administrator
Registered: 2010-06-20
Posts: 8,137

Re: Find all angles θ

hi NakulG

Many thanks for that.  I'll give it a try.  smile

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#6 2017-07-25 22:18:14

NakulG
Member
Registered: 2014-09-02
Posts: 186

Re: Find all angles θ

:-)

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#7 2017-07-25 23:02:57

bob bundy
Administrator
Registered: 2010-06-20
Posts: 8,137

Re: Find all angles θ

hi NakulG

Yep!  Got it now.  That's an inspired substitution!  Thanks once again.  colon bracket with no minus gives a smile on this forum.

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#8 2017-08-01 08:15:26

NakulG
Member
Registered: 2014-09-02
Posts: 186

Re: Find all angles θ

smile

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