Sign In
Ask Question
Cristina
Mathematics
27 July, 20:56
Find cos (a), if cos (a) ^4 - sin (a) ^4 = 1/8
+2
Answers (
1
)
Miranda Cannon
27 July, 21:23
0
3/4, - 3/4
Step-by-step explanation:
Using the difference of squares we can change things around.
cos (a) ^4 - sin (a) ^4
(cos^2 (a) + sin^2 (a)) ((cos^2 (a) - sin^2 (a)) then sin^2 + cos^2 = 1
cos^2 (a) - sin^2 (a) Using the same identity sin^2 = 1 - cos^2
cos^2 (a) - (1 - cos^2 (a))
cos^2 (a) - 1 + cos^2 (a)
2*cos^2 (a) - 1
So let's use this.
2*cos^2 (a) - 1 = 1/8
2*cos^2 (a) = 9/8
cos^2 (a) = 9/16
cos (a) = + / - 3/4
so 3/4 can be positive or negative
Comment
Complaint
Link
Know the Answer?
Answer
Not Sure About the Answer?
Find an answer to your question 👍
“Find cos (a), if cos (a) ^4 - sin (a) ^4 = 1/8 ...”
in 📗 Mathematics if the answers seem to be not correct or there’s no answer. Try a smart search to find answers to similar questions.
Search for Other Answers
You Might be Interested in
Find z when x = 4 and y = 9 if z varies inversely with the product of x and y when x = 2, y = 4, and z = 0.5
Answers (1)
At State University, the cost of tuition is $7278, housing is $3260, the meal plan is $2140, and books cost $1200. How much would you need to pay to attend State University for 4 years given your family will contribute $25,600?
Answers (1)
In a local election between candidate A and candidate B, candidate B got 35 votes, which is 125% as many votes as candidate A. If p represents number of votes won by candidate A, then which proportion can be used to find p?
Answers (2)
Theo is building a garden against his house. He bought two pieces of wood that are each five feet long. He wants to create a triangular garden against his house using the two pieces of wood, without cutting them.
Answers (1)
What is 7 divided by 7 times 56
Answers (1)
New Questions in Mathematics
What is the positive square root of 9/16?
Answers (1)
If 9x-10 evaluate when x = - 5
Answers (2)
For one week, Consuela kept a log of the number of pages she read each night. She read 8 pages on Monday, 11 pages on Tuesday, 10 pages on Wednesday, 7 pages on Thursday, 8 pages on Friday, 8 pages on Saturday, and 10 pages on Sunday.
Answers (1)
What is the radius of a circle who circumference measures 130 26/36
Answers (1)
The rule for a pattern is add 6. The first term is 5. Which of the following numbers is a term in the pattern?
Answers (1)
Home
»
Mathematics
» Find cos (a), if cos (a) ^4 - sin (a) ^4 = 1/8
Sign In
Sign Up
Forgot Password?