Answer:
x = 4
Step-by-step explanation:
Using Pythagoras' identity in the right triangle.
The square on the hypotenuse is equal to the sum of the squares on the other 2 sides, that is
x² + 1² = 9²
x² + 1 = 81 ( subtract 1 from both sides )
x² = 80 ( take square root of both sides )
x = 
= 
= 
× = 4
Answer:
answer: he spent $120
Step-by-step explanation:
20×5=100
100+ the initial $20 spent = $120
#7. C #10. C #11. A #12. C
Answer:
y = 4 sin(½ x) − 3
Step-by-step explanation:
The function is either sine or cosine:
y = A sin(2π/T x) + C
y = A cos(2π/T x) + C
where A is the amplitude, T is the period, and C is the midline.
The midline is the average of the min and max:
C = (1 + -7) / 2
C = -3
The amplitude is half the difference between the min and max:
A = (1 − -7) / 2
A = 4
The maximum is at x = π, and the minimum is at x = 3π. The difference, 2π, is half the period. So T = 4π.
Plugging in, the options are:
y = 4 sin(½ x) − 3
y = 4 cos(½ x) − 3
Since the maximum is at x = π, this must be a sine wave.
y = 4 sin(½ x) − 3
