Answer:
18.0
Step-by-step explanation:
==>Given:
Triangle with sides, 16, 30, and x, and a measure of an angle corresponding to x = 30°
==>Required:
Value of x to the nearest tenth
==>Solution:
Using the Cosine rule: c² = a² + b² - 2abcos(C)
Let c = x,
a = 16
b = 30
C = 30°
Thus,
c² = 16² + 30² - 2*16*30*cos 30°
c² = 256 + 900 - 960 * 0.8660
c² = 1,156 - 831.36
c² = 324.64
c = √324.64
c = 18.017769
x ≈ 18.0 (rounded to nearest tenth)
Short Answer: 18 minutes
Remark
The answer to this problem is less than the smallest time of the two people working together. that fact lets out C and D (38 minutes and 75 minutes). Now you have to choose 15 minutes and 18 minutes. There's a method. No guessing needed.
Givens
Let the time for Sophie = S
Let the time for Simon = M
Let the job to completion = 1
S = 45 minutes
M = 30 minutes
Step One
Convert minutes to hours.
45 minutes = 45 / 60 = 3/4 hour = 0.75 hour
30 minutes = 30 / 60 = 1/2 hour = 0.50 hour
Step Two
Set up the Equation
The formula is a form of job / hour.
Let the time = t that they both have to work
job = 1 in these problems.
1/S + 1/M = 1/t
1/0.75 + 1/0.5 = 1/t
Solve
1 ÷ 0.75 = 1.33333
1 ÷ 0.5 = 2
1.3333 + 2 = 3.33333
3.3333 = 1 / t Multlply both sides by t
3.3333*t = 1
t = 1 / 3.333333333
t = 0.3 of an hour
1 hour = 60 minutes
0.3 hours = x Cross Multiply
x = 60 * 0.3
x = 18 minutes
Answer working together it took them 18 minutes <<<<<
The situation is represented by a drawing with a right triangle where an airplane is at the top corner, the elevation angle (opposite to the airplane) is 70°, the height (vertical leg) is x, and the adjacent leg (horizontal leg) to the 70° angle is 800.
Then, to find the height x, which is the opposite leg to the angle, you can use the tangent ratio, which is opposite leg divided by adjacent leg:
tan(x) = opposite leg / adjacent leg => tan(70°) = x / 800
Answer: tan(70°) = x / 800
