Equation Leading to Height of Tree

[nycmathguy]

Section 6.1

According to the textbook, I am wrong. Why?

 

[MathLover1]

you can't say sin(30)=h/40
given triangle in NOT right triangle

given:
<94 degrees
<30degrees
third angle is 180-(94+30)=56 degrees

base distance 40m
h=?
h/sin(30)=40/sin(56)
h=24.12 m

 

[nycmathguy]

you can't say sin(30)=h/40
given triangle in NOT right triangle

given:
<94 degrees
<30degrees
third angle is 180-(94+30)=56 degrees

base distance 40m
h=?
h/sin(30)=40/sin(56)
h=24.12 m

Yes, you are right. I forgot that Section 6.1 is all about oblique triangles, which do not have a 90° angle. In this tree problem, I see 94°, 40 meters, 30°, which looks like an ASA case.

I can use h/sinA = b/sinB to find the height of the tree.

 

[MathLover1]

yes you can
find the measure of third angle: 180-(94+30)=56 degrees
h/sin(30)=40/sin(56)

 

[nycmathguy]

yes you can
find the measure of third angle: 180-(94+30)=56 degrees
h/sin(30)=40/sin(56)

Very cool. All this stuff is coming back to me. Remember, lack of time is the main reason for the many mistakes. Less problems posted leads to deeper discussions about how to best tackle the questions, particularly word problems.

I haven't been able to keep my promise to do so. You know what, anxiety is a crippling situation. I have been struggling with it since I was a kid. Math is great. God created math but I shouldn't allow my love for numbers to control me. At this I have failed.