What does the notation a1 represent?

a(1) is the first member of a sequence.

Step-by-step explanation:

"a1" could represent "a(1)," where a is the name of a sequence and 1 is the index of the first member of such sequence.  The second member would thus be a(2).

"a1" is not the equivalent of A-1 (which denotes something that's as good as it can get).

area of part 1:

a1=base*height/2=(8+2)*(8-2-2-1)/2=10*3/2=15 ft^2

area of part 2:

a2=length*width=(8+2)*1=10 ft2

area of part 3:

a3=length*width=8*2=16 ft2

total shaded area : a1+a2+a3=41 ft2

total area of the reactangle : a=16*8=128 ft2

total area of the nonshaded region : 128-41=87 ft2

answer:  

step-by-step explanation:

here x represents the height of the pole,

and, the height of the shadow of the pole is 12 feet.

also, the angle of elevation from the top of the pole is 40°,

therefore,

by the low of sine,

which is the required equation for finding the value of x,