1 points SAlgTrig4 74047 Solve the given equation Enter your

+-/1 points SAlgTrig4 7.4.047. Solve the given equation. (Enter your answe SOLUTION.) cos(6) cos cos2(0)-cos(0)-12 = 0 Need Help? Need Help?Read itWatch It needin! Read It 17. 1/1 points I Previous Answers SAlg Trig4 6.2.020

Solution

Solution:

Cos^2() - cos() - 12 = 0

solve quadratic equations y = {-b ± (b^2 - 4ac)}/2a

cos() = {-(-1) ± ((-1)^2 - 4(1)(-12))} / 2*1 = {1 ± (1 + 48)} / 2 = (1 ± 7)/2

cos() = -3, 4

Since 1 cos 1, so equation has no solutions

Solution:

Sin^4 () - cos^4 () + cos^2 ()

= (sin^2 () + cos^2 ()) (sin^2 () - cos^2 ()) + cos^2 ()

By identity sin^2 () + cos^2 () = 1

= (sin^2 () - cos^2 ()) + cos^2 ()

= sin^2 ()