trig help

[sgt_corpse]

A water molecule consists of two hydrogen atoms and one oxygen atom joined as shown. The distance between the nucleus of the oxygen atom and the nucleus of each hydrogen atom is 9.58 X 10 to the negative 9th power cm. The bond angle data is 104.8 degrees. How far apart are the hydrogen nuclei?

 

[Gene]

The law of cosines says
a²=b²+c²-2*b*c*cos(A)
The two legs b & c are 9.58*10^(-9)
A is 104°
a is the distance between the hydrogen atoms. A is the angle opposite side a.

(Note the way multiplication and exponents should be shown.)