## Alfred565 one year ago What is the sine of a 30° angle?

1. anonymous

you need a nice trig cheat sheet

2. anonymous

find the coordinates of the point corresponding to the 30 degree angle the first coordinate is cosine, the second coordinate is sine

3. Alfred565

so, 3/2?

4. Alfred565

@satellite73 and why is the 30 and 60 the same? is it 1/2 or 2/3?

5. Alfred565

3/2*

6. UsukiDoll

my professor told me that to find sin30 we have to look at the 30 degree angle.. and use opposite/ hypotenuse

7. UsukiDoll

|dw:1434591073159:dw| this is a standard 30 degree and 60 degree triangle

8. UsukiDoll

so to look for sin 30 I have to go opposite/hypotenuse so it's like drawing a line from the 1 first and then to the 2 |dw:1434591150637:dw|

9. UsukiDoll

sin x = opposite/hypotenuse so my opposite value is 1 and my hypotenuse is 2.. so sin 30 = 1/2

10. UsukiDoll

but to go for 60 degrees I have to START at the 60 degree angle.

11. UsukiDoll

|dw:1434591242435:dw|

12. UsukiDoll

|dw:1434591275310:dw| so opposite/hypotenuse for 60 degrees is $\frac{\sqrt{3}}{2}$

13. UsukiDoll

the value for triangle is the same but you have to go in a different direction if you want sin 60

14. anonymous

Just a head up. I would learn the Unit circle. It will come in handy later on in your studies.

15. UsukiDoll

luckily for 45 degrees it's easier

16. UsukiDoll

because 45 degrees is everywhere... and the values are the same.. except tan 45 is always 1

17. UsukiDoll

|dw:1434591444328:dw|

18. UsukiDoll

you need to memorize these triangles... they are super useful for calculus....especially when you're not allowed to use a calculator in exams.