### All ISEE Upper Level Math Resources

## Example Questions

### Example Question #11 : Sectors

A giant clock has a minute hand four feet long. Since noon, the tip of the minute hand has traveled feet. What time is it now?

**Possible Answers:**

**Correct answer:**

The circumference of the path traveled by the tip of the minute hand over the course of one hour is:

feet.

Since the tip of the minute hand has traveled feet since noon, the minute hand has made

revolutions. Therefore, hours have elapsed since noon, making the time 1:15 PM.

### Example Question #12 : Sectors

Figure NOT drawn to scale

Refer to the above diagram. is a semicircle. Evaluate given .

**Possible Answers:**

**Correct answer:**

An inscribed angle of a circle that intercepts a semicircle is a right angle; therefore, , which intercepts the semicircle , is such an angle. Consequently, is a right triangle, and and are complementary angles. Therefore,

Inscribed intercepts an arc with twice its angle measure; this arc is , so

.

The major arc corresponding to this minor arc, , has measure

### Example Question #13 : Sectors

Note: Figure NOT drawn to scale

Refer to the above diagram. is a semicircle. Evaluate .

**Possible Answers:**

**Correct answer:**

An inscribed angle of a circle that intercepts a semicircle is a right angle; therefore, , which intercepts the semicircle , is such an angle. Consequently,

Inscribed intercepts an arc with twice its angle measure; this arc is , so

.

### Example Question #14 : Sectors

In the above diagram, radius .

Calculate the length of .

**Possible Answers:**

**Correct answer:**

Inscribed , which measures , intercepts an arc with twice its measure. That arc is , which consequently has measure

.

This makes an arc which comprises

of the circle.

The circumference of a circle is multiplied by its radius, so

.

The length of is of this, or .

### Example Question #15 : Sectors

Figure NOT drawn to scale.

The circumference of the above circle is 120. and have lengths 10 and 20, respectively. Evaluate .

**Possible Answers:**

**Correct answer:**

The length of comprises of the circumference of the circle. Therefore, its degree measure is . Similarly, The length of comprises of the circumference of the circle. Therefore, its degree measure is .

If two secants are constructed to a circle from an outside point, the degree measure of the angle the secants form is half the difference of those of the arcs intercepted - that is,

.

### Example Question #16 : Sectors

Figure NOT drawn to scale.

Refer to the above diagram. and have lengths 80 and 160, respectively. Evaluate .

**Possible Answers:**

**Correct answer:**

The circumference of the circle is the sum of the two arc lengths:

The length of comprises of the circumference of the circle. Therefore, its degree measure is . Consequently, is an arc of degree measure .

The segments shown are both tangents from to the circle. Consequently, the degree measure of the angle they form is half the difference of the angle measures of the arcs they intercept - that is,

### Example Question #17 : Sectors

Figure NOT drawn to scale.

The circumference of the above circle is 100. and have lengths 20 and 15, respectively. Evaluate .

**Possible Answers:**

**Correct answer:**

The length of comprises of the circumference of the circle. Therefore, its degree measure is . Similarly, The length of comprises of the circumference of the circle. Therefore, its degree measure is .

If two chords cut each other inside the circle, as and do, and one pair of vertical angles are examined, then the degree measure of each angle is half the sum of those of the arcs intercepted - that is,

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