Intermediate Geometry : Intermediate Geometry

Study concepts, example questions & explanations for Intermediate Geometry

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Example Questions

Example Question #161 : Intermediate Geometry

Find the length of chord \(\displaystyle ST\).

4

Possible Answers:

\(\displaystyle 14.29\)

\(\displaystyle 16\)

\(\displaystyle 14\)

\(\displaystyle 17.82\)

Correct answer:

\(\displaystyle 16\)

Explanation:

Recall that the perpendicular distance from the center of the circle to the chord will bisect the chord itself.

Thus, we can use the Pythagorean Theorem to find the length of the chord.

\(\displaystyle \text{Radius}^2=\text{distance}^2+\text{half chord}^2\)

Rearrange the equation to solve for the length of half the chord.

\(\displaystyle \text{Half Chord}=\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Now, multiply this value by two to find the length of the entire chord.

\(\displaystyle \text{Chord}=2\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Plug in the given radius and distance to find the length of the chord.

\(\displaystyle \text{Chord}=2\sqrt{10^2-6^2}=2\sqrt{64}=16\)

 

Example Question #162 : Intermediate Geometry

Find the length of chord \(\displaystyle ST\).

6

Possible Answers:

\(\displaystyle 17.50\)

\(\displaystyle 14.21\)

\(\displaystyle 16.12\)

\(\displaystyle 22.47\)

Correct answer:

\(\displaystyle 16.12\)

Explanation:

Recall that the perpendicular distance from the center of the circle to the chord will bisect the chord itself.

Thus, we can use the Pythagorean Theorem to find the length of the chord.

\(\displaystyle \text{Radius}^2=\text{distance}^2+\text{half chord}^2\)

Rearrange the equation to solve for the length of half the chord.

\(\displaystyle \text{Half Chord}=\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Now, multiply this value by two to find the length of the entire chord.

\(\displaystyle \text{Chord}=2\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Plug in the given radius and distance to find the length of the chord.

\(\displaystyle \text{Chord}=2\sqrt{9^2-4^2}=2\sqrt{65}=16.12\)

Make sure to round to two places after the decimal.

Example Question #31 : Chords

Find the length of chord \(\displaystyle ST\).

8

Possible Answers:

\(\displaystyle 28.51\)

\(\displaystyle 34.71\)

\(\displaystyle 33.22\)

\(\displaystyle 29.33\)

Correct answer:

\(\displaystyle 29.33\)

Explanation:

Recall that the perpendicular distance from the center of the circle to the chord will bisect the chord itself.

Thus, we can use the Pythagorean Theorem to find the length of the chord.

\(\displaystyle \text{Radius}^2=\text{distance}^2+\text{half chord}^2\)

Rearrange the equation to solve for the length of half the chord.

\(\displaystyle \text{Half Chord}=\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Now, multiply this value by two to find the length of the entire chord.

\(\displaystyle \text{Chord}=2\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Plug in the given radius and distance to find the length of the chord.

\(\displaystyle \text{Chord}=2\sqrt{24^2-19^2}=2\sqrt{215}=29.33\)

Make sure to round to two places after the decimal.

Example Question #32 : Chords

Find the length of the chord \(\displaystyle ST\).

10

Possible Answers:

\(\displaystyle 9.80\)

\(\displaystyle 9.14\)

\(\displaystyle 9.96\)

\(\displaystyle 9.50\)

Correct answer:

\(\displaystyle 9.80\)

Explanation:

Recall that the perpendicular distance from the center of the circle to the chord will bisect the chord itself.

Thus, we can use the Pythagorean Theorem to find the length of the chord.

\(\displaystyle \text{Radius}^2=\text{distance}^2+\text{half chord}^2\)

Rearrange the equation to solve for the length of half the chord.

\(\displaystyle \text{Half Chord}=\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Now, multiply this value by two to find the length of the entire chord.

\(\displaystyle \text{Chord}=2\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Plug in the given radius and distance to find the length of the chord.

\(\displaystyle \text{Chord}=2\sqrt{5^2-1^2}=2\sqrt{24}=9.80\)

Make sure to round to two places after the decimal.

Example Question #33 : Chords

Find the length of the chord \(\displaystyle ST\).

9

Possible Answers:

\(\displaystyle 32.66\)

\(\displaystyle 39.05\)

\(\displaystyle 31.59\)

\(\displaystyle 36.28\)

Correct answer:

\(\displaystyle 36.28\)

Explanation:

Recall that the perpendicular distance from the center of the circle to the chord will bisect the chord itself.

Thus, we can use the Pythagorean Theorem to find the length of the chord.

\(\displaystyle \text{Radius}^2=\text{distance}^2+\text{half chord}^2\)

Rearrange the equation to solve for the length of half the chord.

\(\displaystyle \text{Half Chord}=\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Now, multiply this value by two to find the length of the entire chord.

\(\displaystyle \text{Chord}=2\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Plug in the given radius and distance to find the length of the chord.

\(\displaystyle \text{Chord}=2\sqrt{27^2-20^2}=2\sqrt{329}=36.28\)

Make sure to round to two places after the decimal.

Example Question #34 : Chords

Find the length of the chord \(\displaystyle ST\).

11

Possible Answers:

\(\displaystyle 26\)

\(\displaystyle 24\)

\(\displaystyle 21.56\)

\(\displaystyle 29.60\)

Correct answer:

\(\displaystyle 24\)

Explanation:

Recall that the perpendicular distance from the center of the circle to the chord will bisect the chord itself.

Thus, we can use the Pythagorean Theorem to find the length of the chord.

\(\displaystyle \text{Radius}^2=\text{distance}^2+\text{half chord}^2\)

Rearrange the equation to solve for the length of half the chord.

\(\displaystyle \text{Half Chord}=\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Now, multiply this value by two to find the length of the entire chord.

\(\displaystyle \text{Chord}=2\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Plug in the given radius and distance to find the length of the chord.

\(\displaystyle \text{Chord}=2\sqrt{13^2-5^2}=2\sqrt{144}=24\)

 

Example Question #35 : Chords

Find the length of the chord \(\displaystyle ST\).

12

Possible Answers:

\(\displaystyle 21.44\)

\(\displaystyle 19.85\)

\(\displaystyle 24.09\)

\(\displaystyle 22.63\)

Correct answer:

\(\displaystyle 22.63\)

Explanation:

Recall that the perpendicular distance from the center of the circle to the chord will bisect the chord itself.

Thus, we can use the Pythagorean Theorem to find the length of the chord.

\(\displaystyle \text{Radius}^2=\text{distance}^2+\text{half chord}^2\)

Rearrange the equation to solve for the length of half the chord.

\(\displaystyle \text{Half Chord}=\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Now, multiply this value by two to find the length of the entire chord.

\(\displaystyle \text{Chord}=2\sqrt{\text{Radius}^2-\text{Distance}^2}\)

Plug in the given radius and distance to find the length of the chord.

\(\displaystyle \text{Chord}=2\sqrt{12^2-4^2}=2\sqrt{128}=22.63\)

Make sure to round to two places after the decimal.

Example Question #36 : Chords

Chords 1

Figure NOT drawn to scale.

Refer to the above diagram.

True, false, or undetermined: \(\displaystyle AX = 6\).

Possible Answers:

True

False

Undetermined

Correct answer:

True

Explanation:

If two chords intersect inside a circle, they cut each other into segments such that the product of the lengths of the portions of one chord is equal to that of the lengths of the portions of the other chord. In other words, 

\(\displaystyle AX \cdot XB = CX \cdot XD\)

Set \(\displaystyle XB= 18, CX = 12, XD= 9\), and solve for \(\displaystyle AX\):

\(\displaystyle AX \cdot 18 = 12\cdot 9\)

\(\displaystyle AX \cdot 18 = 108\)

\(\displaystyle AX \cdot 18\div 18 = 108 \div 18\)

\(\displaystyle AX = 6\).

Example Question #37 : Chords

A circle with a radius of 10 centimeters is shown below. What is the area, in square centimeters, of the shaded region of the circle?

9

Possible Answers:

\(\displaystyle 36\pi -48\)

\(\displaystyle 36\pi\)

\(\displaystyle 24\)

\(\displaystyle 100\pi -48\)

\(\displaystyle 100\pi -36\)

Correct answer:

\(\displaystyle 100\pi -48\)

Explanation:

14

When a chord is intercepted by a perpendicular line segment originating at the center of the circle, the chord is bisected, or cut in half. From the figure, you should notice that the base of the triangle is also the chord of the circle.

Thus, you can use the Pythagorean theorem to find the half of the chord that acts as the other leg of the right triangle that is created.

\(\displaystyle \text{Half Chord}=\sqrt{\text{radius}^2-\text{leg}^2}\)

\(\displaystyle \text{Half Chord}=\sqrt{10^2-6^2}=\sqrt{64}=8\)

Multiply this by \(\displaystyle 2\) to find the length of the entire chord.

\(\displaystyle \text{Length of chord}=\text{Base of Triangle}=16\)

Next, find the area of the triangle.

\(\displaystyle \text{Area of Triangle}=\frac{1}{2}bh\)

\(\displaystyle \text{Area of Triangle}=\frac{1}{2}(16)(6)=48\)

Next, find the area of the circle.

\(\displaystyle \text{Area of Circle}=\pi r^{2}\)

\(\displaystyle \text{Area of Circle}=\pi\times 10^2=100\pi\)

Finally, find the area of the shaded region.

\(\displaystyle \text{Area of Shaded Region}=\text{Area of Circle}-\text{Area of Triangle}\)

\(\displaystyle \text{Area of Shaded Region}=100\pi-48=266.2 \text{ cm}^{2}\)

Example Question #1 : Quadrilaterals

Given: Rhombuses \(\displaystyle ABCD\) and \(\displaystyle EFGH\).

\(\displaystyle AB = EF\)

True, false, or undetermined: Rhombus \(\displaystyle ABCD \cong\) Rhombus \(\displaystyle EFGH\).

Possible Answers:

Undetermined

True

False

Correct answer:

Undetermined

Explanation:

Two figures are congruent by definition if all of their corresponding sides are congruent and all of their corresponding angles are congruent.

By definition, a rhombus has four sides of equal length.  If we let \(\displaystyle s_{1}\) be the common sidelength of Rhombus \(\displaystyle ABCD\) and \(\displaystyle s_{2}\) be the common sidelength of Rhombus \(\displaystyle EFGH\), then, since \(\displaystyle AB = EF\), it follows that \(\displaystyle s_{1} = s_{2}\), so corresponding sides are congruent. However, no information is given about their angle measures. Therefore, it cannot be determined whether or not the two rhombuses are congruent.

 

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