Join TSR now and get all your revision questions answeredSign up now

Easy addition formulae question

    • Thread Starter
    Offline

    3
    ReputationRep:
    tan of 15 degrees
    Online

    3
    ReputationRep:
    (Original post by APersonYo)
    tan of 15 degrees
     \displaystyle \tan 30^{\circ } = \frac{2\tan 15^{\circ } }{1-\tan^2 15^{\circ }} .
    Offline

    1
    ReputationRep:
    What the person above said... I think 😁😁


    Posted from TSR Mobile
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by B_9710)
     \displaystyle \tan 30^{\circ } = \frac{2\tan 15^{\circ } }{1-\tan^2 15^{\circ }} .
    What then?
    Online

    3
    ReputationRep:
    (Original post by APersonYo)
    What then?
    You know the value of tan30, let t be tan15 and solve a quadratic in t.
    Online

    3
    ReputationRep:
    (Original post by APersonYo)
    tan of 15 degrees
    Personally I would go with saying tan(15) = tan(60-45) and then expand using the addition formula for tan.

    And if you're not familiar with the double angle formulae yet then this may be a better approach. If you haven't seen the double angle formulae then B_9710's method just uses tan(30) = tan(15 + 15).
 
 
 
Poll
How are you feeling about your exams so far?
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

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