Silly way to remember the addition formulae

This is just something I came up with to help me remember the addition formulae for C3 trig. It helped me :-P x

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Sin(A +/- B)

Sin ( A + B) = sinAcosB + cosAsinB

The signs are the same on both sides of the identity

The sin and cos' are separate

Sin ( A - B) = sinAcosB - cosAsinB

1 of 2

Cos (A +/- B)

Cos (A + B) = cosAcosB - sinAsinB

Cos (A - B) = cosAcosB + sinAsinB

The signs are contrasting on both sides of the identity

The sine's and the cos' are collected together

2 of 2


Christgirl 94


At least I'm not the only one who remembers things this kind of way! I like it!



do u have any other methhods like this?

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