7-3: TEKS Practice

  • 1. Find the number of degrees in the third angle of the triangle.

    A triangle with angles measuring 43°, 100°, and x°.

  • 2. An architect is designing a home. What is the measure of the missing angle of the roof?

    A triangular roof with angles measuring 31°, 99°, and x°.

  • 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?

    A slide forms a triangle with the ground and the stairs. The ground and the stairs meet at a right angle. The slide meets the ground at an angle measuring 49° and meets the stairs at an angle measuring x°.

  • 4. Mental Math Find the value of the missing angle of the right triangle.

    A right triangle with angles measuring x° and 60°.

  • 5. In ΔQRS, mR is 20° more than mQ and mS is 70° more than mQ. Find mR.

    Triangle QRS. Angle Q measures x°. Angle R measures (x + 20)°. Angle S measures (x + 70)°.

  • 6. For the figure, find the value of the variable x and mQ.

    Triangle PQR. Angle P measures (x − 18)°. Angle Q measures (x + 90)°. Angle R measures x°.

  • 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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Table of Contents

Digits, Grade 8, Volume 1, Homework Helper Unit A: Number and Operations Unit B: Proportionality Unit C: Expressions, Equations, and Relationships English/Spanish Glossary Formulas Math Symbols Formulas Measures Properties