My Math Forum Rhombus.

 Algebra Pre-Algebra and Basic Algebra Math Forum

 January 4th, 2014, 12:56 PM #1 Senior Member   Joined: Nov 2013 Posts: 434 Thanks: 8 Rhombus. ABCD is Rhombus. Measuring the angle (A)=40 Point m belongs to the segment AD Measuring the angle (m BD)=30 find Measuring the angle mCD
January 4th, 2014, 06:42 PM   #2
Global Moderator

Joined: Dec 2006

Posts: 19,515
Thanks: 1745

It's easy to show that it's 10° by using trigonometry.

A geometrical proof is achievable, based on the diagram below.

[attachment=0:28nbddm5]Rhombus.gif[/attachment:28nbddm5]
Attached Images
 Rhombus.gif (2.8 KB, 78 views)

 January 4th, 2014, 09:26 PM #3 Senior Member   Joined: Nov 2013 Posts: 434 Thanks: 8 Re: Rhombus. can you send the by using trigonometry. solve
January 4th, 2014, 10:00 PM   #4
Math Team

Joined: Oct 2011

Posts: 13,115
Thanks: 913

Re: Rhombus.

Nice one Skip! I got to angleDCM = angleBMC - 40, but tires started spinning at that point...

Quote:
 Originally Posted by mared can you send the by using trigonometry. solve
Well, maybe someone will type out the whole solution for you, but not me...
I can supply a hint if YOU're willing to do some work:
let the side lengths = 1
then, since triangle ABM is isosceles and angleAMB = 100, then AM = BM = .5 / SIN(50)

 January 5th, 2014, 04:41 AM #5 Global Moderator   Joined: Dec 2006 Posts: 19,515 Thanks: 1745 Further hint: using .5 = sin(30°), MD = 1 - BM = (sin(50°) - sin(30°))/sin(50°) = 2cos(40°)sin(10°)/sin(50°) = 2sin(10°).

 Tags rhombus

 Thread Tools Display Modes Linear Mode

 Similar Threads Thread Thread Starter Forum Replies Last Post Albert.Teng Algebra 3 October 24th, 2013 02:28 AM Albert.Teng Algebra 6 November 22nd, 2012 12:03 AM daivinhtran Algebra 3 September 14th, 2011 12:05 AM winner Algebra 5 January 21st, 2011 09:16 PM Mathmen Algebra 1 October 20th, 2008 01:18 PM

 Contact - Home - Forums - Cryptocurrency Forum - Top