### 3-6: TEKS Practice

• 1. Find the number of degrees in the third angle of the triangle. • 2. An architect is designing a home. What is the measure of the missing angle of the roof? • 3. There is a slide in the back of the school. The stairs for the slide go straight up. The angle made with the slide and the ground is 49°. What is the value of x? • 4. Mental Math Find the value of the missing angle of the right triangle. • 5. In △ QRS, mR is 20° more than mQ and mS is 70° more than mQ. Find mR. • 6. For the figure, find the value of the variable x and mQ. • 7.

• a. Writing If the measures of two angles of a triangle are 100° and 19°, what is the measure of the third angle?

• b. Explain how a straight angle is related to the angles of a triangle.

• 8. Reasoning An art class is designing a sign to put by the entrance to the school. The sign is in the shape of a triangle and has one angle that is 87° and another which is 42°.

• a. What is the measure of the third angle?

• b. Explain how you could determine if the triangle is acute, right, or obtuse without finding the third angle.

• 9. Error Analysis On a math test the students are given a right triangle. One of the acute angles has a measure of 55°. One student says that the measure of the other acute angle is 125°.

• a. What is the measure of the other acute angle?

• b. What error might the student have made?

• A. The student only subtracted the right angle from 180°.

• B. The student subtracted the sum of the two given angles from 360°.

• C. The student added the right angle and the given acute angle, but did not subtract the sum from 180°.

• D. The student only subtracted the acute angle from 180°.

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