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A special case of angles called the half angles are often expressed in terms of ‘t’. This again helps with solving certain types of equations that might have half angles! This is part of the Prelim Maths Extension 1 Syllabus from the topic Trigonometric Functions: Further Trigonometric Identities. In this post, we will explore t formulae.

Some equations for this topis are as follows, where A = \frac{\theta}{2}

  • cos(A) = \frac{1-t^2}{1-t^2}
  • sin(A) = \frac{2t}{1+t^2}
  • tan(A) = \frac{2t}{1-t^2}


Let’s learn more with some videos.

Part 1


Part 2


Part 3


Part 4

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