Trig Formulae and Trig equations Flashcards
What is the Double Angle Formulae
sin2A = 2sinAcosA
cos2A = 2cos2A  1
= 1  2sin2A
= cos2A – sin2A
3cos2x – 5cosx – 2 = 0 what happens when you Let p = cosx p = ? x = ? cosx = ?
3p2 – 5p  2 = 0 (3p + 1)(p 2) = 0 p = cosx = 1/3 x = cos1( 1/3) x = 109.5 and 250.5 cosx = 2
The exact value of sinx
sinx = 2sin(x/2)cos(x/2) sinx = 2 (¼ + √(42  12) ) sinx = ½ + 2√15)
Addition Formulae
sin(A ± B) = sinAcosB cosAsinB
+

cos(A ± B) = cosAcosB sinAsinB
What do we consider to be the double angle formulae
sin2A and cos2A
Formulae for sin (A + B) and cos (A + B)
ssin(A ± B) = sinAcosB cosAsinB
+ = tan (A + B)
 tanA + tanB
cos(A ± B) = cosAcosB sinAsinB 1  tanA tanB
How are the addition formulae appear?/ what does it look like?
(a + β)
why is the addition formulae used?
to express the sine and cosine of the sum of two angles in term of sines and cosines of the individual angles