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could u explain that again / draw us this diagramvulgarfraction said:Trig identities: someone taught me this is in Year 10, it's the most useful thing I've ever learnt (EDIT: trig-wise...) and I scribble it in pencil whenever I need it:
- draw three lines intersecting like an asterisk, with one horizontal, and the rest 60 degrees from each other
-from top row, label clockwise: sin cos cot cosec sec tan
-write '1' in the middle where the lines intersect
What this means:
-when you get an inverted triangle, sum of squares of top two is square of bottom
-across a line, each function (of x) is the same as the other function (of 90 - x)
-around the hexagon each function is the product of the two on each side
-opposites are reciprocals
Bloody useful. =) And if you have trouble, try working backwards, finding other ways of expression what you need to prove, etc.
that's how it should be done.undalay said:could u explain that again / draw us this diagram.
For me i just have sin^2 + cos^2 = 1
and divide this by whatever i need. If i need sec^2 thats 1/cos^2.
So divide the whole thing by cos^2
Tan^2 + 1 = Sec^2