So here is one thing that might help. Look at both the 1st and 3rd triangles, they have a right angle, just like the one you are trying to figure out. The centemeters is 4 for the longest side and the decimal, 0.57, is going to be multiplied 4 times. The decimal would be 2.28 when multiplied, and the angle is the same as the two triangles I spoke at the second sentence. x is equal to 2.28 but we need to change it to 1 decimal place, meaning that it is 2.3.
Hope this helped!
Nate