Evaluating Cosine Using A Table

Question

The table shows the cosine and sine values for several angles. What is the value of $$\cos\left(\frac{3\pi}{4}\right)$$?

| Angle (radians) | Cosine                          | Sine                           |
|-----------------|---------------------------------|--------------------------------|
| $$\pi/4$$      | $$\frac{\sqrt{2}}{2}$$         | $$\frac{\sqrt{2}}{2}$$         |
| $$3\pi/4$$     | $$-\frac{\sqrt{2}}{2}$$        | $$\frac{\sqrt{2}}{2}$$         |
| $$\pi/6$$      | $$\frac{\sqrt{3}}{2}$$         | $$\frac{1}{2}$$               |
| $$5\pi/6$$     | $$-\frac{\sqrt{3}}{2}$$        | $$\frac{1}{2}$$               |

Accepted Answer

$$-\frac{\sqrt{2}}{2}$$

Answer

$$-\frac{1}{2}$$

Answer

$$\frac{1}{2}$$

Answer

$$\frac{\sqrt{2}}{2}$$

Rank	User	Correct Count	Attempt Count	Total Time	Score
#1	fahidalia08	2	2	0m 19s	181
#2	mihikadarbha	2	2	0m 38s	162
#3	germaingutierrez753	1	1	0m 00s	100
#4	andrew.hsia9	1	1	0m 04s	96
#5	mahmoudjibrin08	1	1	0m 04s	96
#6	majk30881	1	1	0m 04s	96
#7	sanvirrao12	1	1	0m 10s	90
#8	vaibhav.vemuri	1	1	0m 11s	89
#9	chunxiangxu.cxu	1	1	0m 11s	89
#10	hekim4066	1	1	0m 13s	87

Angle (radians)	Cosine	Sine
$\pi/4$	$\frac{\sqrt{2}}{2}$	$\frac{\sqrt{2}}{2}$
$3\pi/4$	$-\frac{\sqrt{2}}{2}$	$\frac{\sqrt{2}}{2}$
$\pi/6$	$\frac{\sqrt{3}}{2}$	$\frac{1}{2}$
$5\pi/6$	$-\frac{\sqrt{3}}{2}$	$\frac{1}{2}$

Evaluating Cosine Using A Table

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