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Paper rectangle ABCD is folded in such a way that the fold passes through point B, and so A coincides with point H where H ∈ CD. BK is the folding line where K ∈ AD. m∠BKD = 120°. If BK = 28 cm, find BC.

 Feb 9, 2020
 #1
avatar+531 
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Paper rectangle ABCD is folded in such a way that the fold passes through point B, and so A coincides with point H where H ∈ CD. BK is the folding line where K ∈ AD. m∠BKD = 120°. If BK = 28 cm, find BC.

BK = 28 cm

AK = sin(30°) * 28 = 14cm

AN = cos(30°) * 14 = 12.125cm

AH = 2 * AN  = 24.25cm

AD = cos(30°) * 24.25 = 21cm

AD = BC = 21 cm    indecision        

 

 

 Feb 9, 2020
edited by Dragan  Feb 9, 2020
edited by Dragan  Feb 9, 2020
edited by Dragan  Feb 9, 2020
 #2
avatar+11696 
+1

Paper rectangle ABCD is folded in such a way that the fold passes through point B, and so A coincides with point H where H ∈ CD. BK is the folding line where K ∈ AD. m∠BKD = 120°. If BK = 28 cm, find BC.

laugh

 Feb 9, 2020
edited by Omi67  Feb 9, 2020

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