Trigonometric Sum and Difference Identities - (Addition Formulae) | ExamSolutions

Here I introduce you to the trigonometric sum and difference identities for sine, cosine and tangent functions. Sometimes known as the addition formulae.

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[sea]

Love how precise and quick your videos are! Thanks

[al-anoud-]

Thank you so much
I understand it better than how the text book explains it

[MafiaCoder]

Good thing these are given in the formula sheet, even easier.

[harvindgrewal]

What is the point of being able to write it out differently if it means the same thing?

[Toyahan]

Is there a video for the proof of this ?

[Cyno]

on your website, the 'what are they' link under aqa, c4 core maths section is the same as the proving identity link.

[Askarvi]

Just rewrite tan (A+-B) as sin(A+- B)/cosine (A +- B), then write it out with your sine and cosine addition formulas. so tan(A+B) would be sin(A+B)/ cos(A+B) which is (sinAcosB + cosAsinB) / (cosAcosB - sinAsinB) if I'm not mistaken. Then divide it by cosAcosB. and simplify, then rewrite as tan.

[georgehenna]

How would you expand tan ( x + pi/2 ) ? Thanks

[msechost]

Tarrific stuff, cannot believe i forgot how to use some the identities

[abaswarsame]

are these formulas not on the formula sheet already

[emad]

sir, how are these useful in math and real life ?

[Jocularious]

Thanks for the help, most appreciated.
 Could you do some calculus, area
under a curve and other calculus
techniques? If so that would be a major
help. Kindest regards.

[msechost]

If you can only prove to me the add or sub formula for the tan, i would be more than pleased.

[ChromeAutomaton]

Have you made a mistake in the second one for cos where you have the + and - sign the wrong way around?

[ExamSolutions_Maths]

Not at all. You need to take care with this one.

[georgehenna]

Is tan ( A + B ) = tan ( A - B )? Thanks

[jorgealbarran]

This would actually be useful to me of they'd actually give me the angles(and not this (1/root of 3) and I were able to use the calculator.

[NicsMP]

I wish I coud rent your math knowledge... I am the lowest in my class. :(