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August 6th, 2019, 02:17 PM   #1
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How do I calculate missing side and angles of this trapezoid?

Hi there.

I've been trying to figure out how to calculate side bc of the trapezoid I've attached to this post. Side ab = 28.693, side ad = 612.651 and side dc = 31.7705. Angle c = 90 degrees and angle b is equal to 90 degrees. How on earth does one go about calculating the length of side bc and it's angle in relation to ad and then how does one also go about calculating what angles d and a are ?

Kind regards
Edwin
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 trig problem.jpg (4.6 KB, 3 views)

August 6th, 2019, 02:55 PM   #2
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$\cos{d} = \dfrac{31.7705-28.693}{612.651}$

you should be able to figure it all out from here
Attached Images
 trapezoid.jpg (23.5 KB, 1 views)

Last edited by skeeter; August 6th, 2019 at 02:57 PM.

 August 7th, 2019, 02:20 AM #3 Newbie   Joined: Aug 2019 From: South Africa Posts: 8 Thanks: 0 Hi there Skeeter, thank you for helping me once more. Could you please confirm for me if this is correct ? cos d = (31.7705−28.693)÷612.651 d = arccos(3.0775÷612.651) d = 89.712 degrees bc = 612.651×sin89.712 bc = 612.643 Kind regards Edwin
August 7th, 2019, 05:56 AM   #4
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Quote:
 Originally Posted by edwin1576 cos d = (31.7705−28.693)÷612.651 d = arccos(3.0775÷612.651) d = 89.712 degrees bc = 612.651×sin89.712 bc = 612.643
correct

 August 7th, 2019, 06:37 AM #5 Newbie   Joined: Aug 2019 From: South Africa Posts: 8 Thanks: 0 Thank you Skeeter, much appreciated.

 Tags angles, calculate, missing, side, trapezoid

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