McGraw Hill Integrated II, 2012
MH
McGraw Hill Integrated II, 2012 View details
Mid-Chapter Quiz
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Exercise 11 Page 749

Two arc measures are known. Find one of the remaining two.

Value of x: 11
Chord Length: 31

Consider the given diagram.

Two circles, each with a chord drawn

In the right circle the chord divides the circumference into two arcs. The major arc has a measure of 284^(∘) and the minor arc we have denoted B^(∘). Note that the arcs are adjacent arcs. Let's recall the Arc Addition Postulate.

Arc Addition Postulate

The measure of the arc formed by two adjacent arcs is the sum of the measures of the two arcs.

Since the arc formed by these two adjacent arcs is a circumference, the sum of their arc measures is 360. 284+ B=360 ⇕ B = 76 We notice that the minor arc in both circles have the same measure, and we know that the circles are congruent. For congruent arcs in congruent circles the corresponding chords are congruent.

Two circles, each with a chord drawn
We can write an equation using that the chords have the same length. 3x-2=2x+9 Let's solve this equation.
3x-2=2x+9
Solve for x
3x=2x+11
x=11
We find the length of the chords by substituting 11 for x in one of the expressions. 3x-2 ⇒ 3(11)-2=31