Chapter 2

  1. 1.  ∠ 1 +  ∠ 3 + 90 °  = 180 ° (sum of angles of a triangle) ∠ 3 = 52 ° (vertical angles) ∠ 1 = 180 °  − 90 °  − 52 °  = 38 ° 

  2. 2.  ∠ 2 +  ∠ 4 = 180 ° (straight angle) ∠ 4 = 52 ° (corresponding angles) ∠ 2 + 52 °  = 180 °  ∠ 2 = 128 ° 

    A diagram of lines and a ray.
  3. 3. Two right triangles. The first has a leg of 10.0 feet and another leg of 8.0 feet. The other has a leg of 25.0 feet and another leg of x units.

    x8.0 = 25.010.0x = 8.0(25.0)10.0 = 20.0ft

  4. 4. Use Hero’s formula:

    s = 12(24.6 + 36.5 + 40.7) = 50.9 cmA = 50.9(50.9 − 24.6)(50.9 − 36.5)(50.9 − 40.7) = 443 cm2

  5. 5. d2 = 1252 + 170d = 1252 + 1702 = 211 ft

    A rectangle with length 170 feet, width 125 feet, and diagonal d.

  6. 6. A = 12h(b1 + b2) = 12(2.76)(9.96 + 4.70) = 20.2 m2

  7. 7. Let m = mass of block

    1. m = 0.92 × 103(0.403) = 59 kg

    2. A = 6(0.402) = 0.96 m2

  8. 8. c = 2πrA = 4πr221.0 = 2πr = 4π(10.5π)2 = 4(10.52)πr = 10.5π = 140 cm2

  9. 9. V = 13πr2h = 13π(2.082)(1.78) = 8.06 m3

  10. 10.  ∠ ACO + 64 °  = 90 ° (tangent perpendicular to radius) ∠ ACO = 26 °  ∠ A =  ∠ ACO = 26 ° (isosceles triangle)12CD¯  = 26 ° (intercepted arc)CD¯  = 52 °  ∠ 1 = 52 ° (central angle)

    A diagram of a circle.
  11. 11.  ∠ CBO +  ∠ 1 + 90 °  = 180 ° (sum of angles of triangle) ∠ CBO + 52 °  + 90 °  = 180 °  ∠ CBO = 180 °  − 52 °  − 90 °  = 38 °  ∠ 2 +  ∠ CBO = 180 ° (straight angle) ∠ 2 + 38 °  = 180 °  ∠ 2 = 142 ° 

  12. 12. r = 12(2.25) cmp = 3(2.25) + 12(2π) [ 12 (2.25) ]  = 10.3 cm

    A rectangle has one side measuring 2.25 centimeters completed by a dashed line. A semicircle falls into the plane of the rectangle; the dashed line is its diameter.

  13. 13. A = 2.252 − 12π [ 12(2.25) ] 2 = 3.07cm2

  14. 14. A = 12(50)[ 0 + 2(90) + 2(145) + 2(260) + 2(205) + 2(110) + 20]  = 41 , 000 ft2

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