Question

Find the value of \[\cos {270^o}\]

Answer 1

Hint: Note that, since \[270^\circ \] is greater than \[90^\circ \], it is located in the third quadrant.
Alternatively, draw the graph for y = cosx and find y when \[x = 270^\circ \]

Complete step-by-step answer:
We know \[270^\circ \]is greater than \[90^\circ \]and is located in the third quadrant.
Therefore,
\[\cos {270^o}\]
\[ = \cos \left( {\dfrac{{3\pi }}{2}} \right)\]
= 0
Therefore \[\cos {270^o}\]=0


Note:

Also, from the graph of \[y{\text{ }} = {\text{ }}cosx\]
we can see, cosine of the angles that are odd multiples of $\dfrac{\pi }{2}$ , is always zero.
Therefore \[\cos {270^o}\]= 0