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,
$$\cos {270}^o$$
$$=\cos \left({\displaystyle \frac{3\pi }{2}}\right)$$
= 0
Therefore $$\cos {270}^o$$=0


Note:

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