Question
Elspeth knows that .rs 9.42 cm. What would she need to do to find the circumference?
She could multiply 9.42 by 2.
She could multiply 9.42 by .
She could divide 9.42 by 2 to find the radius, and then square the radius.
She could divide 9.42 by & to find the radius, and then multiply 9.42 by the radius.
She could multiply 9.42 by 2.
She could multiply 9.42 by .
She could divide 9.42 by 2 to find the radius, and then square the radius.
She could divide 9.42 by & to find the radius, and then multiply 9.42 by the radius.
Answers
Answered by
GPT-4o mini
To find the circumference of a circle when given the radius, you need to use the formula for circumference, which is:
\[ C = 2 \pi r \]
where \( r \) is the radius.
Since Elspeth knows that \( r = 9.42 \) cm, she should:
1. Multiply 9.42 by 2 to find \( 2r \).
2. Multiply the result by \( \pi \) to find the circumference.
Given the options you provided:
- **She could multiply 9.42 by 2.** (This is the first step, but she also needs to multiply by \( \pi \) to find the circumference.)
- **She could multiply 9.42 by \( \pi \).** (This is not correct on its own, as she also needs to multiply by 2.)
- **She could divide 9.42 by 2 to find the radius, and then square the radius.** (This is incorrect for finding circumference, as it does not relate to the given radius of 9.42 cm.)
- **She could divide 9.42 by 2 to find the radius, and then multiply 9.42 by the radius.** (This is not correct since it involves dividing the radius that is already known and does not lead to the circumference calculation.)
In conclusion, the correct approach to find the circumference is to multiply 9.42 by 2 (and later by \( \pi \)), but none of the provided options fully articulate the complete correct method for finding the circumference.
\[ C = 2 \pi r \]
where \( r \) is the radius.
Since Elspeth knows that \( r = 9.42 \) cm, she should:
1. Multiply 9.42 by 2 to find \( 2r \).
2. Multiply the result by \( \pi \) to find the circumference.
Given the options you provided:
- **She could multiply 9.42 by 2.** (This is the first step, but she also needs to multiply by \( \pi \) to find the circumference.)
- **She could multiply 9.42 by \( \pi \).** (This is not correct on its own, as she also needs to multiply by 2.)
- **She could divide 9.42 by 2 to find the radius, and then square the radius.** (This is incorrect for finding circumference, as it does not relate to the given radius of 9.42 cm.)
- **She could divide 9.42 by 2 to find the radius, and then multiply 9.42 by the radius.** (This is not correct since it involves dividing the radius that is already known and does not lead to the circumference calculation.)
In conclusion, the correct approach to find the circumference is to multiply 9.42 by 2 (and later by \( \pi \)), but none of the provided options fully articulate the complete correct method for finding the circumference.