well, cosC = adjacent / hypotenuse, so ...
Note that this is just a 3-4-5 triangle, magnified by 18
1. For ABC what is the value of cosC.
adjudant= 54
hypotnuse=90
opposite=72
3 answers
So 0.8
From
c²=(a²+b²)-2abcosC
cosC=((a²+b²)-c²))/2ab)....
Diagram first then you can't go wrong
a=54,b=90 c=72
(a²+b²)=2916+8100=11016
C²=72²=5184
(a²+b²)-c²=11016-5184=5832
2(ab)=2(54)(90)=9720
cosC=5832/9720=0.6
c²=(a²+b²)-2abcosC
cosC=((a²+b²)-c²))/2ab)....
Diagram first then you can't go wrong
a=54,b=90 c=72
(a²+b²)=2916+8100=11016
C²=72²=5184
(a²+b²)-c²=11016-5184=5832
2(ab)=2(54)(90)=9720
cosC=5832/9720=0.6
1 answer