If 7²=B²+C², and C=0,6 times B; how much is B?

Question

In a small rectangular, we're trying to find the height and width.
We only have the following data:

The diagonal is 7" (A=7)
And the Width is 0,6x the height (C=0.6xB)

What's the answer, and how do you get the answer?

Btw, this is no school task, this is just for me to calculate if the eeepc has a big enough screen for my liking.

(All 4 corners are 90°)

Answer 1

7² = B² + C²

Since C = 0.6 x B, we can substitute that in the initial equation:

7² = B² + (0.6B)² <--- simplify
49 = B² + 0.36B² <--- add common terms
49 = 1.36B² <--- divide by 1.36
36.029 = B² <--- take the square root
B = 6

since B = 6, we know that C = 0.6 x 6 = 3.6

Answer 2

7² = B² + (0.6² B²)
49 = B² + 0.36 B²
49 = 1.36 B²
B² = 49 / 1.36
B = 6
C = 3.6

Dimensions are:-
B = 6 " , C = 3.6 "

Answer 3

C = 0.6B
A² = B² + C²
    = B² + (0.6B)²
    = B² + 0.6²B²
    = B² + 0.36B²
    =1.36B²

A = √(1.36B²)
   = √1.36 √(B²)
7 = B√1.36
B = 6.0024504799878093082528044327675
   ≅ 6

http://i233.photobucket.com/albums/ee195/DWRead/ProDigit.jpg

Answer 4

B=6.00245
C = 3.60147