Usually called "half of base times height", the area of a triangle is given by the formula below.Area=ba2whereb  is the length of the base
a  is the length of the corresponding altitude
You can choose any side to be the base. It need not be the one drawn at the bottom of the triangle. The altitude must be the one corresponding to the base you choose. The altitude is the line perpendicular to the selected base from the opposite vertex.
In the figure above, one side has been chosen as the base and its corresponding altitude is shown.
 
        
        
        
She has 648 shirts. 
Work:
Lisa has 42 pineapples. 4 + 2 = 6
Johnny has 6 marbles. 
42 + 4 + 2 + 6 = 54
54 + 5 + 4 = 63
63 + 6 + 3 = 72
But 72 is a multiple of 6!
Let's go further:
72 * 6 = 432
Now let's look at the word 'shirt'. 
The middle letter is I. 
I is the 9th letter of the alphabet. 
Remember the number 72?
72*9 = 648
        
             
        
        
        
Answer:
7 = -x^2 +16
x^2 -16 = 7
x^2 -23 = 0
Using quadratic equation
x = -0 +- sqrt (23^2 - 4*1*23) / 2 * 1
x = sqrt (0 - -92) / 2
x = sqrt (92) / 2
x1 = 4.7958
x2 = -4.7958
(I tried to answer your  question - even though you posted no question - AND you posted no graphics)
Step-by-step explanation: