Hostname: page-component-78c5997874-xbtfd Total loading time: 0 Render date: 2024-11-11T09:35:30.535Z Has data issue: false hasContentIssue false
  • English
  • Français

101. sin (α + β) from Sine Rule; cos (α + β) from Cosine Rule

Published online by Cambridge University Press:  03 November 2016

A. G. Sillitto
A. G. Sillitto*
Affiliation:
Jordanhill College of Education, Glasgow
Get access Rights & Permissions [Opens in a new window]

Abstract

An abstract is not available for this content so a preview has been provided. Please use the Get access link above for information on how to access this content.
Image of the first page of this content. For PDF version, please use the ‘Save PDF’ preceeding this image.'
Type
Class Room Notes
Information
The Mathematical Gazette , Volume 47 , Issue 359 , February 1963 , pp. 58
Copyright
Copyright © Mathematical Association 1963

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Notes

(i) The proofs hold for all acute angles α, β.

(ii) With angle ACB obtuse, the formulae for sin (α — β) and cos (α — β) are obtained similarly Again α, β must be acute, and consequently α — β also.

(iii) No. 1 is virtually the first proof given on p. 63 of the Associa-tion's Trigonometry Report, where explicit use is made of the formula a = b cos C + c cos A (which happens not to be included in the syllabus for the Scottish Certificate of Education!). The proof of No. 2 is a little simpler if this formula is not used.