In this:
http://img237.imageshack.us/my.php?image=49711639db7.jpg
angle BCD=140degrees
AB=AC=AD=8
calculate BD
Please show me the way.
Please don't use Cosine Law because this question is in the part of the book that is a lot before the cosine law and there should be a solution without it.
2007-09-11 05:06:37 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
the sketch is a little confusing but this is not a rhombus
2007-09-11 05:15:27 · update #1
It is a rhombus. Thus CD = 8
Now apply Pythagoras theorem.
2007-09-11 05:13:57 · answer #1 · answered by ag_iitkgp 7 · 0⤊ 0⤋
angle BCD = 140
so angle BAD = 180 - 140
= 40 (sum of the opposite angles in
quadrilateral = 180 degrees)
in triangle ABD
AB = AD = 8
So ABD is isosceles triangle
Angle ABD = angle ADB = (180 - 40)/2 = 70 degrees
so BD/sin BAD = 8/sin ADB (sine rule)
BD = 8 sin BAD/sin ADB
= 8 Sin 40/sin 70
= 8* (0.9628)
= 7.70 units
2007-09-11 13:03:05 · answer #2 · answered by mohanrao d 7 · 1⤊ 0⤋