a/Sin(A) = b/Sin(B) = c/Sin(C) b C / | a / _| A B c
We know that a = 70 degrees and A = 25 foot So 70/Sin(25) = Something We also know we want C, and that c = 90 degrees So 70/Sin(25) = 90/Sin(C) Then you have to rearrange the equations. Start with Multiply all by Sin(C) So [Sin(C)][70/Sin(25)] = 90 Then divide everything by 70/Sin(25) So Sin(C) = 90/[70/Sin(25)] Now you want to isolate C, so Sin-1 everthing So C = Sin-1{90/[70/Sin(25)]} So C = 32.91309534 To the nearest tenth, 32.9ft Hope that helps :)