
Trigonometry Trigonometry Math Forum 
 LinkBack  Thread Tools  Display Modes 
February 15th, 2017, 04:14 AM  #1 
Newbie Joined: Feb 2017 From: America Posts: 2 Thanks: 0  Finding a side of a triangle
Please view the image provided for the question. Also please attempt to explain the working out of the question, thanks.

February 15th, 2017, 04:51 AM  #2 
Math Team Joined: Jul 2011 From: Texas Posts: 2,751 Thanks: 1401  Let the total side opposite the 70 degree angle be $y$ ... $y= \sqrt{15^2+30^22(15)(30)\cos(70)}$ So, you've got $y$ Let the top angle be $A$ ... $\dfrac{\sin{A}}{30} = \dfrac{\sin(70)}{y} \implies A = \arcsin\left[\dfrac{30\sin(70)}{y}\right]$ Top smaller triangle has angles $A$, $40$, and $(140A)$ $\dfrac{x}{\sin{A}}=\dfrac{15}{\sin(140A)}$ You should be able to get $x$ from here ... 

Tags 
finding, side, triangle 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Finding side of a triangle  Smack01  Geometry  6  April 25th, 2016 07:54 PM 
Finding the angle of a triangle from two known side CM lengths?  matheus  Trigonometry  5  April 3rd, 2015 01:45 AM 
Finding the length x of the side of a triangle?  matheus  Trigonometry  2  March 31st, 2015 09:06 PM 
Finding Side length of Rhombus inside Isosceles Triangle.  Spaghett  Algebra  8  June 24th, 2011 07:52 PM 
Missing side of a triangle  manich44  Algebra  8  March 19th, 2010 08:56 AM 