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.
+1490 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 
