cos (2x) = cos x
2 cos^2 x -1 = cos x using the double angle formula
2 cos ^2 x -cos x -1 =0
factor
(2 cos x+1) ( cos x -1) = 0
using the zero product property
2 cos x+1 =0 cos x -1 =0
2 cos x = -1 cos x =1
cos x = -1/2 cos x=1
taking the arccos of each side
arccos cos x = arccos (-1/2) arccos cos x = arccos 1
x = 120 degrees x=-120 degrees x=0
remember you get 2 values ( 2nd and 3rd quadrant)
these are the principal values
now we need to add 360
x = 120+ 360n x=-120+ 360n x = 0 + 360n where n is an integer
Answer:
10
Step-by-step explanation:
2x3=6
16/4=4
4x3-(6-4)
6-4=2
4x3-(2)
4x3=12
12-(2)
12-2=10
Resposta:
Primer rectangle:
Amplada = 11
Longitud = 14
Segon rectangle:
Amplada = 12
Longitud = 15
Tercer rectangle:
Amplada = 13
Longitud = 16
Explicació pas a pas:
Donat que:
Primer rectangle:
Amplada = x
Longitud = x + 3
2n rectangle:
Augment de la dimensió d'1 cm respecte al primer rectangle;
Amplada = x + 1
Longitud = x + 4
3r rectangle:
Augment de la dimensió de 2 cm respecte al primer rectangle;
Amplada = x + 2
Longitud = x + 5
Suma dels tres perímetres del rectangle:
Perímetre d'un rectangle: 2 (l + O)
Primer rectangle:
2 (x + x + 3) = 2 (2x + 3) = 4x + 6
2n:
2 (x + 1 + x + 4) = 2 (2x + 5) = 4x + 10
3r:
2 (x + 2 + x + 5) = 2 (2x + 7) = 4x + 14
Suma de perímetres = 162
(4x + 6 + 4x + 10 + 4x + 14) = 162
12x + 30 = 162
12x = 162 - 30
12x = 130
x = 11
Per tant,
Primer rectangle:
Amplada = 11
Longitud = 11 + 3 = 14
2n rectangle:
Amplada = 11 + 1 = 12
Longitud = 11 + 4 = 15
3r rectangle:
Amplada = 11 + 2 = 13
Longitud = 11 + 5 = 16
Answer:
17 1/2
Step-by-step explanation:
21 - 3 1/2 = 17 1/2
Given:
The expression is
To find:
The expression which is not a correct way to rewrite the given expression.
Solution:
We have,
Using distributive property, we get
Using distributive property the given expression can rewritten as:
Only the expression in option A is not a correct way to rewrite the given expression because 
is not distributed to 
properly.
Therefore, the correct option is A.
