Step-by-step explanation:
in this situation
A+B =D
When you see the symbol "△", this denotes a triangle. Now combine the symbol with the letters FGH, this becomes △FGH, meaning a triangle FGH, with F, G, and H as the three points.
Now, the symbol "∠" means angle and "m∠" means the measure of an angle. So m∠F means the angle at the point F, m∠G means the angle at the point G, and m∠H means the angle at the point H. (I'll attach a diagram of this triangle).
Now we have to determine m∠H, which is the angle at point H. To do that, we have to find the value of
. To do that, we have to use one of the laws of a triangle, which is:
The sum of angles in a triangle = 180°. This means when we add all the angles in a triangle, it sums up to 180°. Let's do that.

Now that we have found the value of x as 18°, we can substitute its value to determine the angle H.

I hope you understand the explanation.
Answer:
18.7 feet far
Step-by-step explanation:
Based on the information given we can conclude that our set up will be a Right triangle (i.e. one angle is 90°), where the hypotenuse will be denoted by the guy wire of
and angle of 21° is the angle formed between then hypotenuse and the base (i.e. ground).
Thus we want to find the base length (lets call it
) of this triangle, so we can use trigonometry as we have one angle and the hypotenuse, as follow:

So the base is approximately 18.7 feet far from the tree of the anchored wire.
True, look at a tissue box the bottom is the same size as the front