Answer:
see explanation
Step-by-step explanation:
(3)
Given cosΘ = - 
Then by Pythagoras' theorem the third side is 3 ( 3,4, 5 triangle )
Since Θ in second quadrant then sinΘ > 0
sinΘ = 
Using the trigonometric identity
sin2Θ = 2sinΘcosΘ, then
sin2Θ = 2 ×
× -
= - 
(4)
Using the trigonometric identity
cos(x - y) = cosxcosy + sinxsiny
note cos15° = cos(45 - 30)°
cos(45 - 30) = cos45cos30 + sin45sin30
= (
×
) + (
×
)
= 
Answer:
434.9 cm³
Step-by-step explanation:
Volume of a sphere: 4/3πr³
Substitute the information to find the volume.
4/3π(4.7)³ = 434.9
Answer:
SA=94
Step-by-step explanation:
SA= 2(4*5) + 2(4*3) + 2(5*3)
SA=2(20) + 2(12) + 2(15)
SA=40 + 24 + 30
SA=94
Volume of cone: pi * r^2 * h/3
Given volume, height
942in^3 = 3.14 * r^2 * 9/3
942in^2 = r^2 * 9.42
Divide by 9.42
r^2 = 100, r = -10, 10
Cannot be negative so...
Solution: radius is 10 in.