Re: A level maths help
12
Original post
by HugfhsvhThere are ways of finding sin and cos from tan by just using the sin2 and cos2 identity without expressing the identity using tan2
@Muttley79
Reply 1
Original post
by Hugfhsvhsin² alpha+ cos² alpha = 1, and tan alpha = sin alpha / cos alpha. And you wanna skip using 1 + tan² alpha = sec² alpha. Got it.
Let's walk through this together:If you're given tan alpha, what does that even "mean"?
Picture a right triangle.
tan alpha is just the ratio of one side to another... which sides are we talking about here?
Since tan alpha = sin alpha / cos alpha, could you rewrite that to get sin alpha by itself, using cos alpha?
Or the other way around?
Once you've done that, how can you plug it into sin² alpha + cos² alpha= 1 to figure out the real values?
Just take it one step at a time.
Ciao,
Sandro
Reply 2
Hugfhsvh
OP
12
Original post
by NitrotolueneOkay, so you already get the basics:
sin² alpha+ cos² alpha = 1, and tan alpha = sin alpha / cos alpha. And you wanna skip using 1 + tan² alpha = sec² alpha. Got it.
Let's walk through this together:If you're given tan alpha, what does that even "mean"?
Picture a right triangle.
tan alpha is just the ratio of one side to another... which sides are we talking about here?
Since tan alpha = sin alpha / cos alpha, could you rewrite that to get sin alpha by itself, using cos alpha?
Or the other way around?
Once you've done that, how can you plug it into sin² alpha + cos² alpha= 1 to figure out the real values?
Just take it one step at a time.
Ciao,
Sandro
sin² alpha+ cos² alpha = 1, and tan alpha = sin alpha / cos alpha. And you wanna skip using 1 + tan² alpha = sec² alpha. Got it.
Let's walk through this together:If you're given tan alpha, what does that even "mean"?
Picture a right triangle.
tan alpha is just the ratio of one side to another... which sides are we talking about here?
Since tan alpha = sin alpha / cos alpha, could you rewrite that to get sin alpha by itself, using cos alpha?
Or the other way around?
Once you've done that, how can you plug it into sin² alpha + cos² alpha= 1 to figure out the real values?
Just take it one step at a time.
Ciao,
Sandro
Mate ik how to do this
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