pi/4 = 45 degrees. That defines an isoceles right triangle (45-45-90), where the opposite and adjacent sides are the same, and the hypotenuse is square root of 2 times as long.
Cosine is adjacent/hypotenuse = 1/sqrt(2), or sqrt(2)/2 expressed without a radical in the denominator.
The difference between cos and cos-inverse is that cos goes from an angle to the ratio of sides, while cos-inverse goes from the ratio of sides to the angle. If you have the angle and need to know the ratio of adjacent to hypotenuse, use cos. If you have the ratio of sides and need to know the angle, use cos-inverse.
You use cosine to get sides, and inverse-cosine to get angles. Now to cos(pi/4):
This problem is in radiants so you need to know that pi in radiants is equal to 180 degrees. Just substitute it in: cos(180/4) which is the same as cos(45). And without using a calculator, you can know that cos(45) is equal to the square-root of 2, over two. For the visual, think that "s" is square-root: cos(45)=s2/2 done.
to find cos what ever your trying to find the cos of add 90 degrees multiply by 2 then by pi divide by 360 once you get that number estimated (pi goes on forever) then take that radian (spelling?) and use this formula put the radian in for X
Comments
pi/4 = 45 degrees. That defines an isoceles right triangle (45-45-90), where the opposite and adjacent sides are the same, and the hypotenuse is square root of 2 times as long.
Cosine is adjacent/hypotenuse = 1/sqrt(2), or sqrt(2)/2 expressed without a radical in the denominator.
The difference between cos and cos-inverse is that cos goes from an angle to the ratio of sides, while cos-inverse goes from the ratio of sides to the angle. If you have the angle and need to know the ratio of adjacent to hypotenuse, use cos. If you have the ratio of sides and need to know the angle, use cos-inverse.
cos(pi/4) = the sqrt(2)/2
pi/4 is 180/4 which is 45. This means the angles is part of a 45,45,90 triangle. In any triangle like this the cos of 45 = the sqrt(2)/2
use cos to get the side.
use cos-inverse to get the angle.
You use cosine to get sides, and inverse-cosine to get angles. Now to cos(pi/4):
This problem is in radiants so you need to know that pi in radiants is equal to 180 degrees. Just substitute it in: cos(180/4) which is the same as cos(45). And without using a calculator, you can know that cos(45) is equal to the square-root of 2, over two. For the visual, think that "s" is square-root: cos(45)=s2/2 done.
-Corkeoes
its pretty much impossible
explaining now:
to find cos what ever your trying to find the cos of add 90 degrees multiply by 2 then by pi divide by 360 once you get that number estimated (pi goes on forever) then take that radian (spelling?) and use this formula put the radian in for X
x - x^3/3! + x^5/5! - x^7/7! + 9^9/9!......
numbers go on for ever
so you can never find the exact
cos(pi/4) is sqrt(2)/2
There is no real way to get this answer unless you have it memorized or find away to get it on your calculator (square it or something)
cos is used to get a side and cos inverse is used to get an angle
0.99990604980155050801971795294044