McGraw Hill Math Grade 7 Lesson 26.4 Answer Key Circles

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McGraw-Hill Math Grade 7 Answer Key Lesson 26.4 Circles

Exercises

IDENTIFY

Question 1.
What is the radius of the circle?

Answer:
5,
Explanation:
A radius is a line segment that begins at a circle’s origin and extends to tis circumference.
in the circle , all radii are equal in the length.
So, radius r = 5 units.

Question 2.
What is the radius of the circle?

Answer:
5 cm,
Explanation:
A radius is a line segment that begins at a circle’s origin and extends to tis circumference.
In the circle , all radii are equal in the length.
diameter d = 10 cm
radius r = 5 cm.

Question 3.
Identify the 2 radii and the one chord below.

Answer:
\(\overline{AX}\) and \(\overline{XB}\) radii, \(\overline{AB}\) chord.
Explanation:
line \(\overline{AX}\) and \(\overline{XB}\) are radii lines which are passing though center point.
\(\overline{AB}\) is chord, which is not touching center of the circle.
A line segment that has both the end points on the circumference of the circle is called a chord.

Question 4.
Identify the radius and chord in the figure below.

Answer:
\(\overline{VY}\) radius,
\(\overline{WX}\) is chord.
Explanation:
A radius is a line segment that begins at a circle’s origin and extends to tis circumference.
In the circle , all radii are equal in the length.
\(\overline{VY}\) is a radius line which is passing though center,
and \(\overline{WX}\) is chord.
A line segment that has both the end points on the circumference of the circle is called a chord.

Question 5.
What are the 5 chords formed by inscribing the pentagon inside of the circle below?

Answer:
\(\overline{XY}\), \(\overline{YZ}\), \(\overline{ZV}\), \(\overline{VW}\) and \(\overline{WX}\).
Explanation:
A line segment that has both the end points on the circumference of the circle is called a chord.
pentagon has five chords.
\(\overline{XY}\), \(\overline{YZ}\), \(\overline{ZV}\), \(\overline{VW}\) and \(\overline{WX}\) are chords of the circle.

Question 6.
Using the letters provided, can the diameter in the figure below be named? Explain your answer.

Answer:
No, \(\overline{CD}\) does not go through center point O.
Explanation:
A line segment that has both the end points on the circumference of the circle is called a chord.
\(\overline{AB}\) and \(\overline{CD}\) are chords of the circle

Question 7.
How many ways can you describe the radius in this circle?

Answer:
\(\overline{EA}\), \(\overline{AE}\), \(\overline{EC}\), \(\overline{EB}\), \(\overline{CE}\), and \(\overline{BE}\)
Explanation:
\(\overline{EA}\), \(\overline{AE}\), \(\overline{EC}\), \(\overline{EB}\), \(\overline{CE}\), and \(\overline{BE}\) are radii of the circle,
which are originating at center of the circle and end at on the circumference of the circle.

Question 8.
Which two lines in the circle below are chords?

Answer:
\(\overline{AB}\) and \(\overline{CD}\) are chords of the circle.
Explanation:
A line segment that has both the end points on the circumference of the circle is called a chord.
\(\overline{AB}\) and \(\overline{CD}\) are chords of the circle.

Question 9.
Identify the chord and the diameter below.

Answer:
\(\overline{RA}\) is diameter of the circle,
\(\overline{QA}\) is the chord of the circle.
Explanation:
A line segment that has both the end points on the circumference of the circle is called a chord.
\(\overline{RA}\) is diameter of the circle,
\(\overline{QA}\) is the chord of the circle.

Question 10.
Calculate the area of the circle below. Leave your answer in the form of pi.

Answer:
100π in
Explanation:
Area of the circle = πr²
radius of the circle is 10 in
A = π x 10 x 10
A = 100π in

Calculate the circumference and the area.

Question 11.

Answer:
Circumference = __________________
Area = _____________
Answer:
Circumference = 10π  units.
Area = 25π sq units.
Explanation:
Circumference of the circle C = 2 π r
C = 2 π 5
C = 10π units
Area of the circle = πr²
radius of the circle is 10 in
A = π x 5 x 5
A = 25π sq units.

Question 12.

Circumference = ____________
Area = _____________
Answer:
Circumference = 14π units.
Area = 49π sq units.
Explanation:
Circumference of the circle C = 2 π r
C = 2 π 7
C = 14π units
Area of the circle = πr²
radius of the circle is 7 in
A = π x 7 x 7
A = 49π sq units.