Answer:
15 degrees
Step-by-step explanation:
Draw a horizontal segment approximately 4 inches long. Label the right endpoint A and the left endpoint C. Label the length of AC 4.2 meters. That is the horizontal distance between the eye and the blackboard.
At the right endpoint, A, draw a vertical segment going up, approximately 1 inch tall. Label the upper point E, for eye. Label segment EA 1 meter since the eye is 1 meter above ground.
At the left endpoint of the horizontal segment, point C, draw a vertical segment going up approximately 2 inches. Label the upper point B for blackboard. Connect points E and B. Draw one more segment. From point E, draw a horizontal segment to the left until it intersects the vertical segment BC. Label the point of intersection D.
The angle of elevation you want is angle BED.
The length of segment BC is 2.1 meters. The length of segment CD is 1 meter. That means that the length of segment BD is 1.1 meters.
To find the measure of angle BED, we can use the opposite leg and the adjacent leg and the inverse tangent function.
BD = 1.1 m
DE = 4.2 m
tan <BED = opp/adj
tan <BED = 1.1/4.2
m<BED = tan^-1 (1.1/4.2)
m<BED = 15
Answer: 15 degrees
The answer would be 1,220,000mm.
You can do this if you convert all the measures into one unit. Let us convert all into km.
The first one is already in km, so we do not need to covert it.
Let's start with converting 1,220,000mm to km.
There are 1, 000,000 mm in one km.

So there are 1.22km in 1,220,000mm.
Next, we have 120m. There are 1,000m in 1km.

There are 0.12km in 120m
Now you can see that 1,220,000mm is the longest.
The highest point,the top, or apex it is just like a mountain,its vertex is called an peak
Answer:
From what I can see of the problem, you CANNOT solve for the half-life of U 235 AND then solve for the length of time to determine the 20% decay.
U-235 half-life is 704,000,000 years. (Wikipedia)
The elapsed time formula = half-life * [log (Beginning Amount / ending amount) / log 2]
elapsed time = 7.04 x 10^8 * [log (100 % / 80%) / log 2]
elapsed time =7.04 x 10^8 * [log (1.25) / .30103]
elapsed time =7.04 x 10^8 * [0.096910 / .30103]
elapsed time = 7.04 x 10^8 * 0.321928047
elapsed time = 226,637,000 years
Step-by-step explanation:
The gardener will need to buy 60 feet of fencing. Because the square root of 225 if 15, and 15 times 4 is 60. So, 60 is the perimeter of the garden.