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Math Help - Pythagoras's theorem, sine, cosine, tangent functions

  1. #1
    Junior Member turbod15b's Avatar
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    Pythagoras's theorem, sine, cosine, tangent functions

    1)use Pythagoras's Theorem to find the length of the hypotenuse AB of the right angle triangle

    5 sqaured = 25
    9 sqaured = 81
    81+25=106>sqaure root= 10.3cm?

    2)use Pythagoras's to find the length of side AC on the right angled triangle

    14sqaured+3sqaured=sqaure root?

    3)use the Cosine rule to find the length 'x' in the triangle


    4)find the angle makred '0' in the right angled triangle


    5)find angles A and B in the triangle
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  2. #2
    Junior Member
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    ok simple
    You are capable of doing question 1
    so lets move onto question 2
    we are given the hypotenuse and another side
    since the hypotenuse is the LONGEST side of a triangle, the formula for this will be:
    a^2 = c^2 - b^2

    we have the lengths 14 and 3
    so
    x^2 = 14^2 - 3^2
    = 196 - 9
    = 187
    x = sq. root 187

    3. You have got it wrong here. Well technically since THE "cosine" rule defines a different rule altogther. Here you are using the cosine RATIO.

    so cosine ratio = adj/ hyp
    cos 35 = 6/ x
    x = cos 35/ 6

    4. we are given the opposite and adjacent here. Which means the TAN ratio
    therefore:

    tan x = 20/ 35
    x = tan (inverse, shift + tan) of (20/35)

    5. so lets find angle B first
    so if we use this angle, we are given the opposite and hypotenuse
    which means the SINE ratio

    Sin B = 20/ 60
    B = Sin (inverse) of 20/60
    find that angle
    then because theres 180 degrees in a triangle, you can work out the other one

    (btw, when you do the inverse operations, find out the fraction first, then press shift + (whatever you need) then equals button)
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  3. #3
    Junior Member turbod15b's Avatar
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    thank but u haven't told me the answers and how do u work out the calculation on a scientific calculator
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