Function when r=5: 10 Explanation: A circle with a radius of 5 feet has a diameter of 10 feet.
B
b
Function Notation: A(r)=Ï€ r^2
Function when r=5: 25 π or about 78.5 Explanation: A circle with a radius of 5 feet has an area of 25 π square feet.
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C
c
Function Notation: C(r)=2Ï€ r
Function when r=5: 10 π or about 31.4 Explanation: A circle with a radius of 5 feet has a circumference of 10 π feet.
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Practice makes perfect
a
We are asked to write the given equation in function notation, and evaluate it for a given input value. Let's see an example of function notation.
f(x)=xIn the above equation, x and f(x) represent the input and output respectively. We will use this to rewrite the formula d=2r. This equation expresses the diameter d of a circle in terms of its radius r, where r is the input and d is the output. Let's write this formula using function notation.
d(r)=2r
To evaluate this function for r=5, we will substitute 5 for r in the above equation.
