Posted by **bob** on Friday, February 3, 2012 at 7:28pm.

ABCD is a trapezoid with DC parallel to AB, AB=4, AD=4, angle A=60, angle C=45. Find DC and BC

- geometry -
**Reiny**, Friday, February 3, 2012 at 8:38pm
Make a sketch, marking all the given data

join BD

since AB = AD = 4, the triangle is isosceles, furthermore it is easy to see that it must be equilateral, all angles are 60° and BD = 4

By alternate angles , angle BDC = 60° leaving angle CBD = 75°

Using the sine law,

BC/sin60 = 4/sin45

BC = 4sin60/sin45 = 4.8989 or appr. 4.9

find DC in the same way

- Maths -
**Rohit**, Friday, February 3, 2012 at 10:01pm
Find the radius of a right circular cyilender whose volume is 3080cu.cm and height is 20cm.

- geometry -
**Anonymous**, Saturday, February 4, 2012 at 12:45am
v = pi r^2 h

3080 = pi * 20 * r^2

r^2 = 3080/20pi

r = ...

- geometry -
**rakib**, Monday, February 6, 2012 at 11:20am
The two triangles above are similar. If XZ = 10 cm, YZ = 15 cm, and AC = 18 cm, what is the length of BC?

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