I'd doubt any exams will require you to memorise these ratios, what I can say is just make sure you are able to re-produce them in exam conditions rather than memorising them individually
Hello, furor celtica!
The bad news: Yes, we're expected to know these values.
The good news: They're not that hard to learn.
For 45°, draw a square (side 1), draw a diagonal.Using Pythagorus, the diagonal isCode:* - - - - - - * | * | | _ * | | √2 * | 1 | * | | * | | * 45° | * - - - - - - * 1
And we have: .
For 30° and 60°, draw an equilateral triangle (side 2) and an alitutude.Using Pythagorus, the altitude isCode:* /|\ / | \ / | \ 2 /30°| _ \ 2 / |√3 \ / | \ / 60° | \ * - - - * - - - * 1 1
Then: . . . .
A trick which i used to remember ratios in my earlier classes(when i was new to trigonometry..)
For sine ratio
First, write 0 30 45 60 90 which are the basic ratios.
Write from 0 to 4 under each degree
Divide each by 4Code:0 30 45 60 90 0 1 2 3 4
Take the square roots for each..Code:0 30 45 60 90 0 1 2 3 4 -- -- -- -- -- 4 4 4 4 4
We have the sine ratio.. For co-sine ratio take sin 90 as cos 0 and you are done..Code:0 30 45 60 90 0 1 2 3 4 -- -- -- -- -- 4 4 4 4 4 0 1 1 1 -- -- -- -- 2 2 1