Pz 30 points answer only if you know

an antelope trots 40 m east, then turns at a 45o angle and trots 70 m southeast. which choice gives the correct solution for the resultant?

r^2 = 40^2 + 70^2

r^2 = 40^2 + 70^2 - 2(40)(70) cos 135°

r^2 = 70^2 - 40^2

r^2 = 40^2 - 70^2 - 2(40)(70) cos 45°

Amichelson interferometer operating at a 600 nm wavelength has a 3.02-cm-long glass cell in one arm. to begin, the air is pumped out of the cell and mirror m2 is adjusted to produce a bright spot at the center of the interference pattern. then a valve is opened and air is slowly admitted into the cell. the index of refraction of air at 1.00 atm pressure is 1.00028.how many bright-dark-bright fringe shifts are observed as the cell fills with air?