If the sum of two real number is 21, what is the greatest possible value of their product

Step-by-step explanation:

let th numbers be x and y.

x+y=21

y=21-x

Product P=xy=x(21-x)=21 x-x^2

P'=21-2x

P'=0 gives 21-2x=0,x=21/2

P"=-2

which is less than 0 at x=21/2

so P is greatest at x=21/2

y=21-21/2=21/2

P=21/2 ×21/2=441/4=110.25

answer:   28.56 feet (approx)

step-by-step explanation:

since, triangle abc has measure of angle c equal to 55 degrees, measure of angle abc equal to 90 degrees, and length of bc equal to 20 feet.

we have to find out the measurement of segment ab.

therefore, tan 55° =

but bc = 20 feet.

⇒ tan 55 ° =  

⇒ ab = 20 × tan 55 °

⇒ ab = 20 × 1.42814800674

⇒ ab = 28.5629601348   ≈ 28.56 feet