radomes.openskiesproject.org
ftfd54ertre765r ftfd54ertre765r
  • 11-08-2016
  • Mathematics
Answered

2cos2θ−cosθ−1=0 for −180°≤θ≤180°

I don't get how it is solved

Verified Answer :

caylus
caylus caylus
  • 11-08-2016

Hello,

cos 2t=2cos²t-1

2cos 2t -cos t-1=
==>2(2cos² t -1)-cos t-1=0
==>4cos² t -cos t -3=0
Δ=(1+443=49=7²
cos t= (1+7)/8 or cos t=(1-7)/8
cos t =1 or cos t=-3/4

t=0° or t=138.590377...°

Answer Link

Related Questions

how does SAFFIR put out fires
Which of the following bestdescribes Jonathan Edwardssermon Sinners in the Handsof an Angry Goda sermon intended to scare the congregationto rededicate their li
According to the excerpt above the Gadsden purchase was intended to
Write the sum as a product of the GCF and a sum 39 91
What classes exist in Central America today
the sum of two consecutive integers is 13 find the two integers
The group of polar bears that live along the eastern coast of Russia makes up
Bruce has a bottle that contains 60 of lemon juice and the rest water The bottle has 1 liter of water PARTA Write an equation in one variable that can be used t
Which expression represents the given word phrase the sum of 6 and the quotient of a number n and 5
All of the following are lowlatitude climates EXCEPT a tropical savanna b humid subtropical c dry tropical d humid tropical