Find a · b.
|a| = 9, |b| = sqrt(14), the angle between a and b is 45°

Question

Find a · b.
|a| = 9,    |b| = sqrt(14),    the angle between a and b is 45°

anonymous · Answer

i fi remember right the dot product of the two is a*b*cos(angle)

anonymous · Answer

i used that but got the wrong answer somehow.

anonymous · Answer

i did $$9(\sqrt{14}) \cos(45)$$ and it gave me 23.81

anonymous · Answer

what is the right answer

anonymous · Answer

i haven't been given the right answer yet

anonymous · Answer

are us missing anything in the question because i get the same answer as u

raden · Answer

do u have choices ?

anonymous · Answer

i copied and pasted the exact question on here. I don't have any choices just 5 attempts

anonymous · Answer

I've used 4/5 of my attempts

raden · Answer

actually, ur answer is right. but, maybe the answer wants represent in sqrt form. in trygonometry, we knowed that the exact value of cos45 deg = 1/sqrt(2) or 1/2 * sqrt(2). so, ur calculating can be :
a. b = |a|*|b|*cos45 = 9 * sqrt(14) * 1/sqrt(2) = 9 * sqrt(7)

anonymous · Answer

RadEn could be right i checked my text book and nothing is wrong with the equation

raden · Answer

yeah, the question is not right... but, the answer can be formed sqrt value not decimal, maybe :)

raden · Answer

*is not wrong, i mean :)

anonymous · Answer

thanks a lot. 9(sqrt(7) was the right answer!!

raden · Answer

welcome :)