The ratio of the radii of two circles is 2:3. The diameter of the smaller circle is 15 mm. What is the length of the diameter of
2 answers:
The answer is 11.25 mm.
A diameter of a circle is twice of its radius: d = 2r ⇒ r = d/2
small circle large circle
radius: r1 radius: r2 = ?
diameter: d1 = 15 mm
⇒ r1 = d1/2 = 15/2 mm
Since t<span>he ratio of the radii of two circles is 2:3, we have:
r1 : r2 = 2 : 3
which can also be expressed as:
</span>
<span>
We know that r1 is 7.5, so let's implement it:
</span>
Let's multiply both sides of the by 3r2:
⇒
⇒
A diameter of a circle is twice of its radius: d = 2r ⇒ r = d/2
small circle large circle
radius: r1 radius: r2 = ?
diameter: d1 = 15 mm
⇒ r1 = d1/2 = 15/2 mm
Since t<span>he ratio of the radii of two circles is 2:3, we have:
r1 : r2 = 2 : 3
which can also be expressed as:
</span>
<span>
We know that r1 is 7.5, so let's implement it:
</span>
Let's multiply both sides of the by 3r2:
⇒
⇒
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Answer:
(a)
(b) Domain: <em>(See attachment for graph)</em>
(c)
Step-by-step explanation:
Given
Solving (a): A function; l in terms of w
All we need to do is make l the subject in
Divide through by 2
Subtract w from both sides
Reorder
Solving (b): The graph
In (a), we have:
Since l and w are the dimensions of the fence, they can't be less than 1
So, the domain of the function can be
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To check this
When
When
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<em>See attachment for graph</em>
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Solving (c): Write l as a function
In (a), we have:
Writing l as a function, we have:
Substitute for l in
becomes
