Answer:
x = 3
Step-by-step explanation:
2x + 4 = 10
-4. -4
(2x = 6) ÷ 2
x = 3
The length of the envelope is 6.3 inches
Step-by-step explanation:
Width of the envelope = 3 inches
Diagonal of the envelope = 7 inches
To find:
The length of the envelope.
Let the length of the envelope be 'l'
We can use pythogoras theorem to calculate the length.
l = √(49-9)
l = √(40)
l = 6.3 inches
The length of the envelope is 6.3 inches
9514 1404 393
Answer:
$2505.80
Step-by-step explanation:
After the first exchange, the tourist has ...
$3000(12.90 R/$) = R38,700
After 7 days, she has ...
R38,700 -7(R900) = R32,400
After the second exchange, she has ...
R32,400 × ($1/R12.93) = $2505.80
She gets $2505.80 at the second exchange.
X = 18°
cos 54° = sin 36°
cos 3 x = sin 2 x
cos ( 2 x + x ) = sin 2 x
cos 2 x cos x - sin 2 x sin x = 2 sin x cos x
( cos² x - sin² x ) cos x - 2 sin² x cos x = 2 sin x cos x / : cos x
( divide both sides by cos x )
cos² x - sin² x - 2 sin² x = 2 sin x
1 - sin² x - 3 sin² x - 2 sin x = 0
- 4 sin² x - 2 sin x + 1 = 0 substitution: u = sin x
- 4 u² - 2 u + 1 = 0
u = 2 -√20 / - 4
sin 18° = (√ 5 - 1 )/4 
cos 18° = √( 1² - ((√5 - 1)/4)²
cos 18° = (10+2√5)^(1/2) / 4