Feroy's Blog #?

I can't think of anything cleaver to say at the moment, so I'll just start the blog.

I'm jumping on the Chapter 10 bandwagon, so yeah, don't expect anything original.

The best part about this chapter is that I don't have to use a calculator, which is awesome, because I hate them. So does Annie and Alex Tir, so it must be an Asian thing.

Anyway, two formulas to know:

cos(α+/-β) = cos(α)cos(β) -/+ sin(α)sin(β)
sin(α+/-β) = sin(α)cos(β )+/- cos(α)sin(β)

Ex. Find the exact value of sin 30

Find the values of alpha and beta from the trig chart that add or subtract to get 30. Which would be 60 and 30.

* I'm not 100% sure on this, but alpha is always the bigger number. Again, I'm not 100% on this.

Since we're finding the exact value of sin 30, I want you to guess what formula I'm gonna use. Go ahead, there are no wrong answers, except cos.

sin(60-30) = (√3/2)(√3/2) - (1/2)(1/2)

sin(30) = 3/4 - 1/4

sin(30) = 1/2

That's it.

I actually know what I'm doing so far, and I'm fairly confident I'm going to do better this nine weeks. Well, I hope so.