Answer:
[tex] \frac{13}{2} [/tex]
Step-by-step explanation:
slope of the line that passes thru (5, 3) and (8, A)
[tex] = \frac{a - 3}{8 - 5} \\ \frac{a - 3}{3} [/tex]
the line that is perpendicular to the given line is
6x + 7y + 13= 0
finding the slop of this line :-
[tex]6x + 7y + 13 = 0 \\ 7y = - 6x - 13 \\ y = - \frac{6}{7} x - \frac{13}{7} [/tex]
Comparing with standard equation of a line
y = mx + c
m = - 6/ 7
Since, the two lines are perpendicular to each other the product of their slopes will be - 1
[tex] \frac{a - 3}{3} \times \frac{ - 6}{7} \\ \frac{ - 2(a - 3)}{7} = - 1 \\ - 2a + 6 = - 7 \\ - 2a = - 7 - 6 \\ - 2a = - 13 \\ 2a = 13 \\ a = \frac{13}{2} [/tex]
( canceling the 2 negative signs on both the sides )