Using trigonometry to measure visual angles

[lilyas]

OK i am sooo stuck and i would really appreciate help in answering this question

Question 2a: Assume the tree is 10 m high and viewed from a distance of 30 m. Use Equation 1 to calculate the angle subtended by the tree at the eye? Express your answer in degrees to two decimal places (hint: the answer is near 20 degrees).



GO to the link and look at question 2A picture and equation
http://webspace.qmul.ac.uk/pskorupski/VisionLab/VisualAngles/VisualAngles.htm


Please help i am sooo stuck

 

[mmm4444bot]

Use Equation 1 to calculate the angle subtended by the tree at the eye

Equation 1 is:

\(\displaystyle a = 2 \cdot arctan(\frac{0.5H}{D})\)

Can you "see" from the diagram that symbol H represents the height of the tree? They gave you the value for H.

Symbol D represents the distance from which the tree is viewed. They gave you the value for D.

Symbol a represents the angle subtended by the tree at the eye. They want you to find the value of a.

Substitute the given values for H and D into equation 1, and evaluate to find the angle a.