Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    Dear All,
    I have already sweated over this question for an hour and its starting to get on my nerves. I was hoping if the brightest minds on TSR would mind giving me a helping hand.
    Solve in the interval 0< \theta<180^{\circ}
    2 \cot^2 \theta=7 \mathrm{cosec} \theta-8
    Thanks,
    Saran
    Offline

    12
    ReputationRep:
    change the cot into cosec and form a quadratic, bam!

    2cot^2=2(cosec^2-1)
    Offline

    12
    ReputationRep:
    1+Cot^2theta=cosec^2theta
    Offline

    12
    ReputationRep:
    (Original post by Diaz)
    1+Cot^2theta=sec^2theta
    Aint it cosec?
    Offline

    11
    ReputationRep:
    (Original post by Diaz)
    1+Cot^2theta=sec^2theta
    :nah: It's cosecant:

    \displaystyle 1 + \cot^2(\theta) = \csc^2(\theta)
    Offline

    12
    ReputationRep:
    (Original post by Wesssty)
    Aint it cosec?
    What happens when you do it in your head:rolleyes:
    Edited
    Offline

    0
    ReputationRep:
    (Original post by saran35)
    Dear All,
    I have already sweated over this question for an hour and its starting to get on my nerves. I was hoping if the brightest minds on TSR would mind giving me a helping hand.
    2 \cot^2 \theta=7 \mathrm{cosec} \theta-8
    Thanks,
    Saran
    cot^2(theta) = cosec^2(theta) - 1

    so 2cosec^2theta - 2 = 7cosec theta - 8
    assume cosec theta = y
    2y^2 - 2 =7y-8
    2y^2 -7y + 6 = 0
    (2y-3)(y-2) = 0
    y = 3/2 or 2
    so 1/sin^2(theta) = 3/2 or 2

    sin^2(theta) = 2/3 or 1/2
    then square root everything and solve normally.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: January 30, 2010
The home of Results and Clearing

1,295

people online now

1,567,000

students helped last year

University open days

  1. Bournemouth University
    Clearing Open Day Undergraduate
    Fri, 17 Aug '18
  2. University of Bolton
    Undergraduate Open Day Undergraduate
    Fri, 17 Aug '18
  3. Bishop Grosseteste University
    All Courses Undergraduate
    Fri, 17 Aug '18
Poll
Will you be tempted to trade up and get out of your firm offer on results day?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.