I'm given the inverse version of cos (Cos^-1). How do I find the exact value?
I make it into: Cos = -1, but that's where I get stuck. I need two values to get the angle (cos = a/h), how do I get the other? Thanks!
2007-05-21 20:39:00 · 6 answers · asked by Jorm 3 in Science & Mathematics ➔ Mathematics
You're restricting yourself to the first quadrant. The cosine of 180 is -1. That's just one of those things worth memorizing. So the arccos(-1) = 180, or in radians, π.
The way I remember it is because I know cos(0) = 1 and sin(0) = 0, and on the opposite end (180 degrees) it's the negative of each one. Similarly, cos(90) = 0 and sin(90) = 1 while co(270) = 0 and sin (270) = -1.
Another way to do this is to think of where the curve y = cos(x) hits -1.
2007-05-21 20:42:39 · answer #1 · answered by Anonymous · 2⤊ 0⤋
The 45-45-90 right triangle has sides in proportion 1-1-sqrt(2). We're looking for an angle whose cosine is 1/2 sqrt(2) and that right triangle helps. The answer is arccos[1/2 sqrt(2) ] = Pi/4 If you're looking for the exact value of an inverse trig. function the 45-45-90 and 30-60-90 right triangles should lead you to the correct answer. Just remember the answer should be in radians not degrees. Take Care!
2016-05-19 09:03:18 · answer #2 · answered by anglea 2 · 0⤊ 0⤋
180
2007-05-21 20:57:05 · answer #3 · answered by eyak 1 · 0⤊ 0⤋
the principle value branch of cos is [0,Pi] and values are from [-1,1], cos (2n-1)*pi= -1 where n is the set of all natural numbers.
2007-05-21 20:52:42 · answer #4 · answered by Niranjan 1 · 0⤊ 0⤋
arccos(-1) = (2n - 1)π, n = any integer. The primary value is π.
2007-05-21 21:08:41 · answer #5 · answered by Helmut 7 · 0⤊ 0⤋
180 degrees or pi radians
2007-05-21 20:44:25 · answer #6 · answered by ironduke8159 7 · 1⤊ 0⤋