The third one is the answer im sure
Answer:
Step-by-step explanation:
we would like to solve the following using double-angle formula:
there're <u>4</u><u> </u>double Angle formulas of cos function which are given by:
since the question doesn't allude which one we need to utilize utilize so I would like to apply the second one, therefore
step-1: assign variables
to do so rewrite the given function:
so,
Step-2: substitute:
recall unit circle thus cos300 is ½:
simplify square:
reduce fraction:
simplify substraction and hence,
Answer:
10.69
Step-by-step explanation:
We must first know that the angle of refraction is given by the following equation:
n_water * sin (A_water) = n_air * sin (A_air)
where n is the refractive index, for water it is 1.33 and for air it is 1.
The angle (A) in the air is 22.8 °, and that of the water is unknown.
Replacing these values we have to:
1.33 * sin (A_water) = 1 * 0.387
sin (A_water) = 1 * 0.387 / 1.33
A_water = arc sin (0.2907) = 16.9 °
now for the tank depth:
h = D / tan (A_water)
D = 3.25
Replacing
h = 3.25 / tan 16.9 °
h = 10.69
Therefore the depth is 10.69 meters.
Answer:
121.5
Step-by-step explanation:
40.5*3=121.5
Well, you take 0.199 find the hundredths place, which is the 9 to the left in this example, and decide whether the number to the right of the nine is more than 5, which it is, so we round the 9 up. However, we can't just make it 10 hundredths, so we have to simplify it to 1 tenth and add it onto the tenths place to make 0.20.
