So it tells you that AB = 21 and AD = 28 and you to find what BD + AC is and since BD is the same length as AC you only need to find one of them, then double it There is a formula you use called the Pythagorean theorem The Pythagorean theorem is A²+B²=C² In this problem A = 21 B = 28 and C = the length of BD so it'll look like 21²+28²=Length of BD² or BD²=21²+28² now you find BD first do 21²+28² --> 441+784 --> 1225 Now you know that 21²+28²=1225 so BD²=1225 Then to find BD, you find √1225(square root of 1225) Which is 35 So BD=35 and you want to know what BD+AC is so 35+35=70
