Comprehensive Guide to Solving Angles and Arc Measures in Geometry
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This resource provides step-by-step solutions to various geometric problems involving angles and arc measures. From determining the value of x in equations such as 2x = 84 to exploring angle measures inside and outside circles, it utilizes theorems to simplify and find solutions. The guide also includes examples of real-world scenarios like calculating visible arcs during phenomena such as the Northern Lights. Practice problems and answers help reinforce understanding of key concepts necessary for mastering geometry.
Comprehensive Guide to Solving Angles and Arc Measures in Geometry
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Solve for x. 1. 2x = 84 + 32 1 2 58 ANSWER 2. x = ( 360 – 120) = 0 120 ANSWER
3.180 – x = (( 2x + 4) + 28). 1 2 82 ANSWER 45º ANSWER Solve for x. 4. One-half of the measure of an angle plus its supplement is equal to the measure of the angle. Find the measure of the angle.
= a. m1 12 (130o) (125o) 2 = b. m KJL EXAMPLE 1 Find angle and arc measures Line mis tangent to the circle. Find the measure of the red angle or arc. SOLUTION = 65o = 250o
= m1 12 (210o) for Example 1 GUIDED PRACTICE Find the indicated measure. SOLUTION = 105o
m RST (98o) 2 = for Example 1 GUIDED PRACTICE Find the indicated measure. SOLUTION = 196o
m XY (80o) 2 = for Example 1 GUIDED PRACTICE Find the indicated measure. SOLUTION = 160o
The chords JLand KMintersect inside the circle. (mJM + mLK) xo = 12 12 xo (130o + 156o) = xo = 143 EXAMPLE 2 Find an angle measure inside a circle Find the value of x. SOLUTION Use Theorem 10.12. Substitute. Simplify.
The tangent CDand the secant CBintersect outside the circle. (mAD – mBD) m BCD = 12 12 xo (178o – 76o) = x = 51 EXAMPLE 3 Find an angle measure outside a circle Find the value of x. SOLUTION Use Theorem 10.13. Substitute. Simplify.
The Northern Lights are bright flashes of colored light between 50 and 200 miles above Earth. Suppose a flash occurs 150 miles above Earth. What is the measure of arc BD, the portion of Earth from which the flash is visible? (Earth’s radius is approximately 4000 miles.) EXAMPLE 4 Solve a real-world problem SCIENCE
Because CBand CDare tangents, Also,BC DC and CA CA . So, ABC ADC by the Hypotenuse-Leg Congruence Theorem, and BCA DCA.Solve rightCBA to find thatm BCA 74.5°. (mDEB – mBD) m BCD = CB AB and CD AD 12 12 149o [(360o – xo) –xo] xo 31 The measure of the arc from which the flash is visible is about 31o. ANSWER EXAMPLE 4 Solve a real-world problem SOLUTION Use Theorem 10.13. Substitute. Solve for x.
ANSWER y = 61o for Examples 2, 3, and 4 GUIDED PRACTICE 4. Find the value of the variable.
ANSWER a = 104o for Examples 2, 3, and 4 GUIDED PRACTICE Find the value of the variable. 5.
ANSWER xo 253.7o for Examples 2, 3, and 4 GUIDED PRACTICE 6. Find the value of the variable.
Line t is tangent to the circle. Find the value of x and y. 1. ANSWER 115 Daily Homework Quiz
ANSWER 52 Daily Homework Quiz Line t is tangent to the circle. Find the value of x and y. 2.
ANSWER 25 Daily Homework Quiz Line t is tangent to the circle. Find the value of x and y. 3.
ANSWER x = 81; y = 40.5 Daily Homework Quiz Line t is tangent to the circle. Find the value of x and y. 4.