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Sherman81
Lv 6
Sherman81 asked in Science & MathematicsMathematics · 1 decade ago

Finding the height of a scalene triangle when given 2 angles and 1 side?

i'm only allowed to use sin(A), cos(A), tan(A), Law of Cosines, and Law of Sines to solve this one.

side c = 1200

Angle A = 72

Angle B = 77

i have to find the altitude/height of the triangle. can someone help me.

Update:

A is on the left

B is on the right

c of course makes up AB

i need to find the height from side c to angle C.

Update 2:

i found the answer at answers.com online to be 2159 but how do they get it.

Update 3:

using the formula i found at http://mathforum.org/dr.math/faq/formulas/faq.tria...

i get 1141 which works, so why/how did they come up with 2159.

2 Answers

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  • vinginge
    Lv 7
    1 decade ago
    Favorite Answer

    The 3 angles of a triangle = 180° so C = 180 - (77 + 72) = 31

    Using the Sine Rule : a/Sin 72 = 1200/Sin 31 : a = 1200 x Sin 72/Sin 31 = 2215.89 (2dp)

    Area of triangle = ½ac Sin B

    Area of triangle = ½ base x altitude = ½c x altitude

    Then, ½ac Sin B = ½c x altitude

    Altitude = aSin B = 2215.89 x Sin 77= 2159.10 (2dp)

  • lozandier
    Lv 4
    5 years ago

    Finding Height Of A Triangle

    Source(s): https://shrink.im/a0Cfr
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