U gotta use pythagorean theory So a^2 +b^2 = c^2 C=7 since its the one facing the right angle 5.2^2 + b^2 = c2 27.04 +b^2= 49 Subtract 21.96 from both sides, so ur left with 21.96=b^2 Under the square root and rounded up would equal 4.7 Hope this helps