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# angle between two lines(urgeeent)

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hi,
i want to know that if i know two sides of a triangle can i know the angle between two lines,there is no method in api such as tan inverse , cos inverse etc . please explain with an example its urgent . thanks in advance.

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Prashant
If you only know 2 sides that is not enough to be able to figure out the angle between them. For triangles, to calculate a missing side or angle, you need to hae three things: 2 angles and a side, 2 sides and an angle, 3 sides, or 3 angles. then you can use sin and cosine to figure out the missing peices.
hope that helps

Dave

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Perhaps you're thinking of a right triangle? Then you really know one angle (the right angle) and two sides. In that case, yes, it's possible - in Java the inverse trig functions are found in the Math class - asin(), acos(), atan(). Naturally theswe return values in radians, but you can convert the values to degrees if necessary. Hope that helps...

prashant komaragiri
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Originally posted by Jim Yingst:
Perhaps you're thinking of a right triangle? Then you really know one angle (the right angle) and two sides. In that case, yes, it's possible - in Java the inverse trig functions are found in the Math class - asin(), acos(), atan(). Naturally theswe return values in radians, but you can convert the values to degrees if necessary. Hope that helps...

hi jim,
thanks for ur reply but i think atan is not tan inverse.any othe r solution ??
prashant

Jim Yingst
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Well, I'm quite certain that the atan or arc tan is the "tan inverse", if by that you mean the inverse tangent function, commonly written tan-1. That is, if you input an argument, it returns a value representing an angle in radians between -pi/2 and pi/2 whose tangent is equal to the argument. What makes you think it's not the inverse tangent?

prashant komaragiri
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Originally posted by Jim Yingst:
Well, I'm quite certain that the atan or arc tan is the "tan inverse", if by that you mean the inverse tangent function, commonly written tan-1. That is, if you input an argument, it returns a value representing an angle in radians between -pi/2 and pi/2 whose tangent is equal to the argument. What makes you think it's not the inverse tangent?

ya jim,
i got it thanks very much. actually when i put Math.atan(50/30) and then convert it to degrees it was coming out to be 45 deg that is wrong.thats why i was thinking it is not tan inverse. but when i put 50.0/30.0 in Math.atan it was giving correct value . Thanks again
prashant

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