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About Scotto
Expertise
Any kind of mathematics (calculus, analysis, game theory, linear approximation, finite differences, linear regression, linear programming, numerical analysis, probability, statistics, etc.). I also have answered some questions in Physics (mass, momentum, falling bodies), Chemistry (charge, reactions, symbols, molecules), and Biology.

Experience
Experience in the area: I have tutored students in all areas of mathematics for over 20 years. Education/Credentials: BSand MS in Mathematics from Oregon State University, where I completed sophomore course in Physics and Chemistry. I received both degrees with high honors. Awards and Honors: I have passed Actuarial tests 100, 110, and 135.

Publications
Maybe not a publication, but I have respond to well oveer 3000 questions on the PC. That's around 2,000 in basic math and 1,000 in advanced math.

Education/Credentials
I aquired well over 40 hours of upper division courses. This was well over the number that were required. I graduated with honors in both my BS and MS degree from Oregon State University. I was allowed to jump into a few junior level courses my sophomore year.

Awards and Honors
I have been nominated as the expert of the month several times. All of my scores right now are at least a 9.8 average (out of 10).

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My past clients have been students at OSU, students at the college in South Seattle, referals from a company, friends and aquantenances, people from my church, and people like you.

 
   

You are here:  Experts > Teens > Homework/Study Tips > Calculus > calculus

Calculus - calculus


Expert: Scotto - 6/23/2009

Question
State the exact value, in simple radical form : (NO DECIMALS !!)
1.    sin 225°

2.    tan 3π/4

3.    cos 270°

4.    sin 11π/6

5.  cos 150°  

Answer
1. The sin(225°) can be found by noticing that 225° the same as 180°
+ 45°.  Now the sin() is positive for the first 180° and negative for the second.  The sin(225°) is just -sin(45°).  A 45° angle has sides 1 and hypoteneuse root(2).


2. The tan(3π/4) can be found by knowing that π radians is 180°.
This make 3π/4 radians π/4 radians away from π radians.
The tan(3π/4) would be the same as -tan(π/4), which is -tan(45°).

We both know that is we have a 45° angle, the tan() is 1.


3. cos(270°):  270° is 90° + 180°, and the cos(90°) is 0,
so the cos(270°) is the same thing.


4. sin(11π/6): 11π/6 is the same as 12π/6 - π/6,
so the sin(11π/6) = sin(π/6)
since the sin() is reflective about π/2.


5. cos(150°):  It can be seen that 150° is 180° - 30°,
so the cos(180°) is -cos(30°) since the cos(A) is the same as
-cos(180-A).

The cos(30°) is root(3)/2,
so the cos(150°) is just the negative of that.


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