Answer:

Step-by-step explanation:
The formula for arc length is:

Where Θ is measured in degrees.
We know that the arc length is 8π when the degree is 80. So, substitute 8π for A and 80 for Θ:

Divide both sides by 2π:

Simplify the fraction:

Multiply both sides by 9/2:

So, the radius is 18.
Now, we can find the area of the circle. The formula for the area of a circle is:

Substitute 18 into r:

Simplify:

And we're done!
Answer:
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Step-by-step explanation:
Isolate the variables. You want to get the five on the same side as the ten, so, you add five to both sides.
-4b+2b=15
-2b=15
b= -7.5
I believe. You may want to double check my work though.
L = 15m = 1500cm
b= 30cm
h= 4m= 400cm
So, total volume of the wall= l×b×h
= 1500×30×400= 1,80,00,000 cm^3
Now, volume of one brick= 22×12.5×7.5= 2062.5 cm^3
Volume of wall containing only bricks= total volume of the wall - volume of wall containing mortar
= 1,80,00,000 - (1,80,00,000 × 1/12)
= 1,65,00,000 cm^3
So, no. of bricks = volume of wall containing bricks ÷ volume of one brick
= 1,65,00,000 ÷ 2062.5
= 8000 bricks.
ΔThe Answer to your question is D).<span>109.2%</span>Δ