Feroz's Blog

I'll be going over a little bit of all the sections of chapter 10, as a review for myself. Yeah.

Section 1:

Finding exact values of sin and cos and other stuff. I understood this pretty well, just remember the formulas and the trig chart and you'll be fine.

ex. Find the exact value of sin 75

=sin (45 + 30) = sin45cos30 + cos45sin30

= (1/2)(sqrt2/2) + (sqrt3/2)(sqrt2/2)

= (sqrt6 + sqrt2)/4

Section 2:

Same thing as section 1, but with tan and cot. Again, formulas and trig chart.

ex. Find the exact value of tan 15

=tan (45 - 15) = tan45 - tan15/1 + tan45tan 15

= (sqrt3/3) - 1/1 + (sqrt3/3)(1)

= (sqrt3) -3/(sqrt3) + 3

= 2 - (sqrt3)

Section 3:

Double and Half-Angle formulas. Like, sin2A and cos2A and all that other nonsense.

ex. 2sin45cos45

Sin2A formula = 2sinAcosA

So, sin2A = sin2(45)

= sin 90 = 1

That's all. Wasn't too hard, easier than Chapter 8 and maybe 9, but that's because I didn't study those. Oh well.