Posted by lindsay on Tuesday, May 21, 2013 at 5:39am.
Find the exact value of
1. tan 75 degrees
2. Cos 15 degrees
3. Sin 105 degrees

math  Steve, Tuesday, May 21, 2013 at 11:30am
you know the values for 30 and 45 degrees
use your sum/difference and halfangle formulas
75=45+30
15=30/2
105=90+15

math  hari krishna, Monday, September 21, 2015 at 12:29am
Tan 75 = tan (45 +30)
= tan 45 + tan 30/1tan 45 *tan 30
= (1+ 1/√3)/(11/√3) = √3 + 1/√31
= √3 + 1/√31 (afterationalization )
= 2+√3
cos 15 = cos (45  30)
= cos 45 cos 30+ sin 45 sin 30
=
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