Using Double Angle Identities to Solve Equations, Example 1

[Cornbreadddd]

Good god this material makes me want to blow my brains against the wall.

For whatever reason, mathematics is just completely indigestible to me. Trig makes a little more sense, but I find myself watching these videos and thinking to myself "If I were working this problem, I would have never thought to do that on my own." It's like I would never know where to go next. I have absolutely NO problem at all with difficult sciences, and love organic chemistry with a passion, but this stuff is just so frustrating. 

[anthonyzunno]

My graduation speech, "I'd like to thank patrickJMT for being a better math teacher than all 4 years of bullshit I've endured"

[SVPrelude]

"If I saw a problem like this, just out of no where. The first thing I'd think is... "Holy sh*t""

[breeelam]

Thank you. I've memorized this and have never really been taught how to use it.

[ZariyaJ]

Damn I'm about to take a L on this test

[faa]

I swear the best source of learning math better than textbooks, teachers, and everything.

U always make my life easier

god bless u

[treyatl]

I was with you until you let y=2x. I paused the video and solved it to see if we would get the same solution and we did. But you did it a completely different way. All I did was solve using inverse trig and got 90 degrees. And I know from the unit circle that 90 degrees is equal to pi/2. Then I knew that pi/2 is equivalent to 3pi/2 using the graph of cosine for the given interval.

[stephh]

Thank you. I was panicking before my math final, but luckily I found this video. Very helpful

[danielle]

So where did these identities come from? Do we just accept them?

[لحظةتأمل-طص]

woooow i didn't understood anything

[Km-yilu]

God bless you man. You have such a gift.

[fabiandmello]

When I factorise trig, I find it really easy to sub in cos and sin as a variable such as a or b. then its easy to solve the quadratic and at the end when you have your two answers, you can just sub back in cos or sin instead of a or b.

[moniishak]

you know your good at math when you can do it with a permanent marker

[BulldogLawyer]

You explained it very well and yet it is still very hard to grasp.

[AssyrianKingever]

You always motivate me with your simplestrategies

[alexhanton]

All of these videos are so helpful, maybe I won't fail my final anymore!

[SniperReady]

These contrived problems will likely never see the light of day in real world applications but the underlying concept of simplifying trigonometry with identities is applicable to many science and math based careers. In careers that involve construction, such as engineering and architecture, knowing how to manipulate identities helps you to figure out real world measurements when you only know certain pieces of information.

[dirtydand]

Writing left-handed blocks the view until you're finished and makes it hard to follow what you're talking about as you write. Not sure how to remedy but it could help even more people

[hazmane]

Dear PatrickJMT,
Please come teach at my college! I'll take you for Calc 1, 2, and 3 AND differential equations! (I'm about to finish Trig and it's HARD!)

[Toronto]

im your biggest fan patrick!! go patty!