Here’s a little story that you can use when your kid whines that he or she doesn’t need to do their math homework.
This summer I had a dead Big Leaf Maple tree that needed to come down. The previous owners of my house had wrapped a braided metal cord around the trunk and left it there until it garroted the tree and left it standing threatening my dinning room if it should fall in the wrong direction. This was also a great excuse to play with my chainsaw (as if I needed an excuse). In an attempt to do things safely I needed to figure out how tall the tree was to make sure it wasn’t going to land on my new grill, because I would rather spend an hour stubbornly failing at math then spend 30 seconds moving the grill just in case.
First I measured 25′ out from the base of the tree, because that’s as far as my tape measure goes. Next I downloaded a protractor app on my phone, held it up to my eye and and got the angle from my eye to the top of the tree. Using that information I figured out the other angles and drew out my geometry problem.
I was feeling pretty smug with myself until I realized that I had to figure out 2 triangles now. No problem, I would just remeasure from the ground to the top of the tree and make it easier on myself.
There! Now I had all of the information that I needed to solve this problem and it had only taken me about 10 minutes. Time to solve for ‘X’.
I was pretty good at geometry back in high school, but it’s been 14 years since I had to solve for ‘X’. I knew that there was a way to find the height of my tree if I knew some angles and at least one side, and I knew that I would have to use trigonometry. I remembered that trigonometry meant that I would need to use sine, cosine, or tangent. Now what the hell do those mean again, and how do I use them to protect my grill?
X=sinX / …no, that’s not it. X=(25 x sin(73) / sin(17)). Now that’s a good looking equation! How do I solve that? Duh! By using an online graphing calculator. My tree is 17.598651 feet tall. That’s not right. At this point I was slightly regretting programming my graphing calculator with games in high school.
I eventually texted my brother in-law who does math for a living. Instead of solving for ‘X’ he texted back another equation that I also couldn’t solve.
I finally gave up, moved the damn grill and cut down the tree. It would have hit the grill.
That was the end of that. I put it behind me in a flurry of cutting, splitting, and stacking rounds (I love splitting wood). Now the rainy season is upon us and I need to build a temporary shelter for my woodpile. I want the roof to slope to help shed water and I’d like to cut the uprights at the proper angles to be flush with the slopped roof. That means that I have another right triangle to deal with. This is twice in the same year. I guess that means that I should actually sit down and re-learn trigonometry.