Compound and double angle formulaeAQA A-Level Maths: Flashcards

What these 14 flashcards ask

\sin(A+B)=?
\sin(A-B)=?
\cos(A+B)=?
\cos(A-B)=?
\tan(A+B)=?
\tan(A-B)=?
\sin2A=?
Three forms of \cos2A?
\tan2A=?
Express \cos^2A using \cos2A.
Exact value of \sin75^\circ?
Exact value of \tan75^\circ?
Why should you not divide by \sin\theta in \sin2\theta=\sin\theta?
How does the area method prove \sin(A+B)?

Exam questions on Compound and double angle formulae

Angles $A$ and $B$ are acute, with $\sin A=\frac35$ and $\cos B=\frac{5}{13}$ .
Find the exact value of $\tan(A+B)$ .2 marks
The angle $\theta$ is acute and $\tan\theta=\frac34$ .
Find the exact value of $\tan2\theta$ .2 marks
In this question, work without a calculator and give exact answers. Note that $75^\circ=45^\circ+30^\circ$ .
Show that $\sin75^\circ=\frac{\sqrt6+\sqrt2}{4}$ .3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).