A triangle has sides A, B, and C. Sides A and B are of lengths #7# and #4#, respectively, and the angle between A and B is #pi/3#. What is the length of side C?

1 Answer
Alan P.
Nov 7, 2016

#abs(C)~~6.083# sq.units

Explanation:

Consider the image below:
enter image source here
Remember that
#color(white)("XXX")sin(pi/3)=sqrt(3)/2color(white)("XX")andcolor(white)("XX")cos(pi/3)=1/2#

Based on this we have:
#color(white)("XXX")h=7sin(pi/3) ~~6.0621778265#

#color(white)("XXX")x=7cos(pi/3)=3.5#

#color(white)("XXX")k=4-x=0.5#

#color(white)("XXX")abs(C)=sqrt(h^2+k^2)~~6.0827625303#

Related questions
See all questions in The Law of Cosines
Impact of this question
1406 views around the world
You can reuse this answer
Creative Commons License