Since Mike drove at 65 mph for 3 hours, we have that he traveled:
[tex]3\cdot65=195\text{ miles}[/tex]
for Sandra, we have the following:
[tex]3\cdot70=210\text{ miles}[/tex]
notice that both trajectories with the distance apart segment form a right triangle, then, using the pythagoren theorem, we get:
[tex]x=\sqrt[]{(210)^2+(195)^2}=\sqrt[]{44100+38025}=\sqrt[]{82125}\approx287\text{ miles}[/tex]
therefore, Sandra and Mike are approximately 287 miles apart after 3 hours
