June 5th, 2019, 02:09 PM  #1 
Member Joined: Jan 2019 From: tornto Posts: 48 Thanks: 0  Three ships
Three ships are at points P, Q, and R such that PQ = 2km, PR = 7km, and $\small\angle$QPR = 142$^\circ\!$. What is the distance between Q and R, to two decimal places? Please help. Last edited by skipjack; June 5th, 2019 at 09:02 PM. 
June 5th, 2019, 02:33 PM  #2  
Math Team Joined: Jul 2011 From: Texas Posts: 3,016 Thanks: 1600  Quote:
$QR = \sqrt{PQ^2+PR^2  2PQ \cdot PR \cdot \cos(142^\circ)}$ Last edited by skipjack; June 5th, 2019 at 09:02 PM.  
June 6th, 2019, 02:59 PM  #3 
Member Joined: Jan 2019 From: tornto Posts: 48 Thanks: 0 
my answer is 7.430102967 correct? thanks 
June 6th, 2019, 03:15 PM  #4 
Math Team Joined: Jul 2011 From: Texas Posts: 3,016 Thanks: 1600  no ... also, the directions say two decimal places


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