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#1 2015-04-20 05:00:21

Beverrrn
Member
Registered: 2015-03-09
Posts: 6

Trigonometric Identities

I'm in tears over this homework (think the stress is getting to me...)

1)
a) Given that 5sinθ=2cosθ, find the value of tanθ

b) Solve, for 0≤ x<360° 5sin2x=2cos2x
giving your answers 1dp

2)
a) Show that the equation tan2x=5sin2x can be written in the form (1-5 cos2x) sin 2x=0
b) Hence solve, for 0≤x≤180° tan2x=5sin2x to 1dp, showing clearly how you obtained yours answers

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#2 2015-04-20 05:52:45

Bob
Administrator
Registered: 2010-06-20
Posts: 10,058

Re: Trigonometric Identities

hi Beverrrn

Hey! No tears.  Fun is what we're here for.  smile

Looks like no one has told you that

So if 5sinθ=2cosθ divide by cos and also by 5, and you'll have sin/cos = tan = a fraction straight away.

So then part b falls into place fairly easily.  Solve for 2x and thus for x.  Make sure you find all the answers.

Q2.  Re-write as sin(2x) / cos(2x) - 5sin(2x) = 0 and then is should be possible for you to finish.

If you post your answers, I'll check them for you.

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
Sometimes I deliberately make mistakes, just to test you!  …………….Bob smile

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