How solve this equation where 0.8=0.2 cos (31.4 t) where 31.4 is the unit in radian per second and we want to find t (time)value, the answer is t=0.037 seconds, how to solve it algebraically?

1 Answer
Aug 15, 2015

Answer:

Hi Shafiyah, you cannot really solve this equation because your function goes only from #0.2# to #-0.2# (amplitude) and #0.8# cannot be reached!

Explanation:

If you have #0.8# you have:
#0.8=0.2cos(31.4t)#
#cos(31.4t)=0.8/0.2=4# that cannot be (#cos# goes from #1# to #-1# only!);

If it is: #0.08=0.2cos(31.4t)# then:
#cos(31.4t)=0.08/0.2=0.4#
#31.4t=arcos(0.4)=1.1593#
#t=1.1593/31.4=0.037s#