A key word to remember when doing this type of math is "SOHCAHTOA".
Sine = 
Opposite over
Hypotenuse
Cosine = 
Adjacent over
Hypotenuse
Tangent = 
Opposite over
Adjacent
Since this is a 3, 4, 5 triangle, with the sides just multiplied by 7, the opposite of A which is 28 would be simplified to 4. 
And the Hypotenuse would be simplified to 5.
So, the answer is 4 / 5!
 
        
             
        
        
        
If PQ=7 and QR=10,
P=(7/Q) and R=(10/Q)
Therefore:
PR=(7/Q)(10/Q)
=(70)/Q²
        
             
        
        
        
| u | = √(2² + (-1²)) = √5
| v | = √ ( 1² + (-8)² = √65
cos (u,v) = ( u * v ) / (| u | * | v |) =
 (2 * 1 + ( -1 ) * ( - 8 )) / √5 √ 65 = (2 + 8) / √5 √65 = 10 / (√5 √ 65 )
The length of a larger diagonal:
d 1² = | u |² + 2 |u| |v| + | v |² = 5 + (2 √5 √65 * 10 / √5 √65 )+65
 d 1² = 70 + 20 = 90
d 1 = √ 90 = 3√10
d 2² = 70 - 20 = 50
d 2 = √50 = 5√2
Answer: 
The lengths of the diagonals are: 3√10 and 5√2 .
        
             
        
        
        
Answer:
m = 
Step-by-step explanation:
I'm assuming by m, you mean the slope. 
You have two points. (-11, 5) and (2, -4)
- m = change in y-value ÷ change in x-value
1) Substitute in the points. 
m = 
2) Solve. 
So, the slope would equal  .
.