Please Simplify arccos( cosX * cosY ) ???

[p***@yahoo.com]

If possible. Thanks.

[quasi]

[Please Simplify arccos( cosX * cosY ) ???]
If possible. Thanks.

I think it's about as simple as it's going to get.

quasi

[Roland Franzius]

Post by p***@yahoo.com
If possible. Thanks.

arccos( cos x cos y) -> arccos (1/2 cos(x+y) + 1/2 cos(x-y))
arcos(x) -> pi/2- arctan (sqrt(1-x^2),x)
arcos(x) -> pi/2 + i log( i x +sqrt(1-x^2))

There are formulae for cos(x+y) in terms of products of sin,cos and
consequently nonlinear formulae for (arccos x + arccos y) but not the
other way around

[Barry Schwarz]

Post by p***@yahoo.com
If possible. Thanks.

cos x * cos y = [cos (x+y) + cos (x-y)] / 2

But I don't know it that really qualifies as a simplification.