If the question is how many students are girls, than it's ten(10).
The answer is A, the first one :)
Answer:
Step-by-step explanation:
They want you to see how radius is important. Just remember that one radian is one radius, that should help you see why radius is important.
They ask for the unit circle , that is a circle of one unit for the radius, which makes it super easy to calculate things for it, they ask what is the area, which is that famous formula, π
, then they ask what's its circumference. which is that other famous formula 2πr
so to go all the way around a circle of one unit radius, it's 2π exactly or about 6.28..... units, call it meters, or feet or inches, it doesn't mater here.
the size of the circle doesn't matter here either, b/c we are using the radius , that relaationship doesn't change , all circles, what ever size , have this same relationship between the radius and radians. :P this is handy.
Draw a diagram to illustrate the problem as shown below.
The area of triangle acb is
A₁ = (1/2)*20*h = 10h
The area of trapezoid abcd is
A₂ = (1/2)*(20+12)*h = 16h
The ratio A₁/A₂ is
A₁/A₂ = (10h)/(16) = 5/8
Answer:
The ratio of triangle acb to the area of trapezoid abcd is 5/8.