356,383 views
36 votes
36 votes
Find the value of x.
A. 65
B. 32.5
C. 118
D. 130

Find the value of x. A. 65 B. 32.5 C. 118 D. 130-example-1
User Awiseman
by
3.0k points

2 Answers

20 votes
20 votes

Answer:


D.\ \ 130

Explanation:

1. Approach

Refer to the attached diagram of the figure for further explanation. In this problem, one is asked to solve for the degree measure of arc (x). The easiest method to do so is to use the triangle (CAB). One can solve for the measure of angle (<CBA) by using the tangent to radius theorem. Then one can solve for the measure of angle (CAB) by using the base angles theorem. Then one can use the sum of angles in a triangle theorem to solve for angle (<BCA). Finally, one can use the central angles theorem to solve for the arc (x).

2. Find the measure of angles in the triangle

A. Find the measure of angle (<CBE)

As per the given image, lines (BE) and (AE) are tangent. This means that they intersect the circle at exactly one point. A radius is the distance from the center of a circle to the circumference or outer edge of a circle. All radii in a single circle are congruent. The radius of tangent theorem states that, when a tangent intersects a circle at a point of tangency, and a radius also intersects the point of tangency, the angle between the radius and the tangent is a right angle. One can apply this here by stating the following:


m<CBE = 90

Express angle (<CBE) as the sum of two other angles:


m<CBE = m<CBA + m<ABE

Substitute with the given and found information:


m<CBE = m<CBA + m<ABE


90 = m<CBA + 65

Inverse operations,


90 = m<CBA + 65


25= m<CBA

B. FInd the measure of angle (<CAB)

As stated above all radii in a single circle are congruent. This means that lines (CB) and (CA) are equal. Therefore, the triangle (CAB) is an isosceles triangle. One property of an isosceles triangle is the base angles theorem, this theorem states that the angles opposite the congruent sides of an isosceles triangle are congruent. Applying this theorem to the given problem, one can state the following:


m<CBA = m<CAB = 25

C. Find the measure of angle (<ACB)

The sum of angles in any triangle is (180) degrees. One can apply this theorem here to the given triangle by adding up all of the angles and setting the result equal to (180) degrees. This is shown in the following equation:


m<CAB + m<CBA + m<ACB = 180

Substitute,


m<CAB + m<CBA + m<ACB = 180


25 + 25 + m<ACB = 180

Simplify,


25 + 25 + m<ACB = 180


50 + m<ACB = 180

Inverse operations,


50 + m<ACB = 180


m<ACB = 130

3. Find the measure of arc (x)

The central angles theorem states that when an angle has its vertex on the center of the circle, its angle measure is equivalent to the measure of the surrounding arc. Thus, one apply this theorem here by stating the following:


m<ACB = (x)\\130 = x

Find the value of x. A. 65 B. 32.5 C. 118 D. 130-example-1
User Tynese
by
2.6k points
12 votes
12 votes

Answer:

D. 130

Explanation:

The lines are tangent to the circle therefore 90º which makes 65º + 25º. The small triangle with C is iso so the angle of C would be 130 and equivalent to x