Turn on thread page Beta

A2 Trigonometry help?? watch

Announcements
    • Thread Starter
    Offline

    0
    ReputationRep:
    Hey, can anyonle help me on these questions?
    -180< x <180

    1) sec^2x + tan^2x = 6

    and i got... tan^2x + 1 + tan^2x = 6
    and I can't get any further


    2) 4cos^2x + 5sinex = 3

    I have noo idea how to start this one

    3) tanx + cotx = 2

    dont know what to do here either
    Offline

    15
    ReputationRep:
    For Q1, you know 2tan²x + 1 = 6. So tan²x = 5/2. So tan x = sqrt(5/2). Essentially you just solve for tan x as you would if it were just 'x' or 'y' or whatever .

    For Q2, write cos²x = 1 - sin²x, then you have a quadratic equation in sin x . Again, just treat 'sin x' as if it were 'x' or 'y'.

    For Q3, just multiply both sides by tan x .
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    (Original post by Simba)
    For Q1, you know 2tan²x + 1 = 6. So tan²x = 5/2. So tan x = sqrt(5/2). Essentially you just solve for tan x as you would if it were just 'x' or 'y' or whatever .

    For Q2, write cos²x = 1 - sin²x, then you have a quadratic equation in sin x . Again, just treat 'sin x' as if it were 'x' or 'y'.

    For Q3, just multiply both sides by tan x .
    I would add to Simba's post that you need to consider there are two cases to consider from tan²x = 5/2 and a total of four solutions in that interval.
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Simba)
    For Q1, you know 2tan²x + 1 = 6. So tan²x = 5/2. So tan x = sqrt(5/2). Essentially you just solve for tan x as you would if it were just 'x' or 'y' or whatever .

    For Q2, write cos²x = 1 - sin²x, then you have a quadratic equation in sin x . Again, just treat 'sin x' as if it were 'x' or 'y'.

    For Q3, just multiply both sides by tan x .
    AAH thanks for the help...I've just completed them - its annoying to think that I keep forgetting how to do the simple things to them...like multiplying both sides by tan x :eek:

    Thanks a lot
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: October 13, 2009

University open days

  • Manchester Metropolitan University
    Postgraduate Open Day Postgraduate
    Wed, 14 Nov '18
  • University of Chester
    Chester campuses Undergraduate
    Wed, 14 Nov '18
  • Anglia Ruskin University
    Ambitious, driven, developing your career & employability? Aspiring in your field, up-skilling after a career break? Then our Postgrad Open Evening is for you. Postgraduate
    Wed, 14 Nov '18
Poll
Should Banksy be put in prison?
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

Equations

Best calculators for A level Maths

Tips on which model to get

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.