Trig Identity question
Favorites|Homepage
Subscriptions | sitemap
HOME > Mathematics > Trig Identity question

Trig Identity question

[From: ] [author: ] [Date: 11-05-06] [Hit: ]
and verify that it is true.cos (30) + (cos (30) tan²(30) = sec (30).sec (30) = 1/cos (30). Using that cos (30) = 1/2,Since LHS = RHS, this identity is true when x = 30.......
For the identity cos x + (cos x tan^2 x) = sec x
Show that it is true for x = 30 deg, using exact values

please help i am so stuck on this question
Thanks in advance

-
30 degrees is one of the special angles you should have memorized for the purposes of this class. All you need to do is substitute x=30 into the entire equation, and verify that it is true. So then you must verify that

cos (30) + (cos (30) tan²(30) = sec (30). Start with the RHS

sec (30) = 1/cos (30). Using that cos (30) = 1/2, you get
sec (30) = 2

LHS

cos (30) + (cos (30)tan²(30)) =
(1/2) + ((1/2)(3)) (using that tan (30) = √3)
LHS = 1/2 + 3/2 = 4/2 = 2

Since LHS = RHS, this identity is true when x = 30.
1
keywords: Trig,Identity,question,Trig Identity question
New
Hot
© 2008-2010 http://www.science-mathematics.com . Program by zplan cms. Theme by wukong .