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Math Help - Right angled triangle help

  1. #1
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    Right angled triangle help

    Ok, I have a few questions I need some help with please!

    using a right angled triangle ABC where B = 90 degrees find

    A)BC
    B)AB

    if

    i) AC = 10cm and A =32 degrees
    ii) AC = 12cm and A = 46 degrees
    iii) AC = 6cm and C = 42 degrees

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  2. #2
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    Quote Originally Posted by Kim2425 View Post
    ...
    using a right angled triangle ABC where B = 90 degrees find
    A)BC
    B)AB

    if

    i) AC = 10cm and A =32 degrees
    ii) AC = 12cm and A = 46 degrees
    iii) AC = 6cm and C = 42 degrees
    ...
    Hello,

    use the definitions of Sine or Cosine. With your triangle:

    \sin(A)=\frac{\overline{BC}}{\overline{AC}}

    \cos(A)=\frac{\overline{AB}}{\overline{AC}}

    Now use the given values to calculate the missing one:

    to i)
    \overline{BC}=\overline{AC} \cdot \sin(A) \approx 5.3  \ cm
    \overline{AB}=\overline{AC} \cdot \cos(A) \approx 8.48 \ cm

    to ii)
    \overline{BC}=\overline{AC} \cdot \sin(A) \approx 8.63 \ cm
    \overline{BC}=\overline{AC} \cdot \sin(A) \approx 8.34 \ cm

    to iii)

    90 - C = A = 48. Use the formulas as above:

    \overline{BC}=\overline{AC} \cdot \sin(A) \approx 4.46 \ cm
    \overline{BC}=\overline{AC} \cdot \sin(A) \approx 4.01 \ cm

    EB
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