Liquids<span> are not </span>packed<span> as tightly as </span>solids<span>. And gases are very loosely </span>packed<span>. The spacing of the molecules enables </span>sound<span> to travel much faster through a </span>solid<span> than a gas. </span>Sound<span> travels about four times faster and farther in water than it does in air.</span>
Use pythagorean theorem

to find the opposite side, which is 7.3
so then you can just use inverse sinA=7.3/10 which equals 46.9 degrees