Since pi is equivalent to 3.14 and means 180°, therefore 1.75 which
is about half of pi should be at almost 90°. The cos of a 90° angle which is located on
the y axis should be zero, therefore cos 1.75 must be near zero. However in
this case it is near one, clearly his calculator is in degree mode that is why
he got an erroneous answer.
What Sam
can do to get the correct answer would be to convert his calculator into radian
mode or convert the given 1.75 rad into degrees:
θ = 1.75
rad (180° / π rad)
θ =
100.2676
cos 100.2676
= -0.1782 which is now correct since it
is nearer to zero
