In Exercises 3-6, find m∠1 and m∠2. Tell which theorem you use in each case. (See Example 1.) 3. 4. 5. 6....

In Exercises 3-6, find m∠1 and m∠2. Tell which theorem you use in each case. (See Example 1.)
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In Exercises 7-10, find the value of x. Show your steps. (See Examples 2 and 3.)
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In Exercises 11 and 12, find m∠1, m∠2, and m∠3. Explain your reasoning.
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13. ERROR ANALYSIS Describe and correct the error in the student's reasoning.