• Calculators
jpreher
I am running into an interesting problem on my ti-89 and was wondering if anyone could explain the reason for the following.

I am attempting to solve the following:
$$M=\int_{x}^{y}sin(\theta )*(r-a*cos(\theta ))d\theta$$

r = 0.14
a = 0.09

where,
x = 0 deg
y = 120 deg

The calculator gives me an answer of
$$M = 10.09838$$
This answer is incorrect, so I verified that the ti-89 was in degrees (it was) and decided to try the problem in rads instead to see if it is still incorrect.

now where,
y = 2*pi/3

I get a correct answer of
$$M = 0.17625$$

What is going on here?

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