Could someone explain how I can do this question?

Let M = midpoint of AB

Then

Triangle VMA is a right angle triangle and the angle VME is angle between the planes

14.3^2 = VM^2 + 5.05^2

VM = sqrt( 14.5^2 - 5.05^2)

= 13.37862101

VEM is a right angled triangle with VM the hypotenumse

cos(VME) = 5.05/13.37862101

= 0.3774679017

angle VME = cos^-1(0.3774679017)

= 67.82307341

= 68 deg

Not your best answer?

http://oi65.tinypic.com/106mue0.jpg