358409 (3) [Avatar] Offline
#1
Figure 12.2 on page 263 shows the result of the first formula as 0.2827945994. However, when I try it I get -0.2273593095.
Admittedly I am using a TI83 instead of a TI84 Plus C, but that shouldn't make any difference. So, either it's a mistake in the book, or I am missing the obvious.

Regards, Chris
christopher.mitchell (11) [Avatar] Offline
#2
Chris, thanks for sending along this errata note. Are you in Radian or Degree mode? If you're in Degree mode (that calculator in the screenshot is in Radian mode, as you can see from its status area), you'll get a different answer.

Christopher
358409 (3) [Avatar] Offline
#3
I'm definitely in Radian mode. In fact, if I put it in Degree mode (something I had tried) I get an answer of 0.2136613841.

So, neither Radian mode nor Degree mode, result in the answer shown in the screen shot.

Regards, Chris
christopher.mitchell (11) [Avatar] Offline
#4
Chris, I pulled out my calculator and got to the bottom of this. The expression in the book is sin((5pi/4)^2): note that the entire fraction is squared, since the fraction bar does not extend underneath it. You computed sin((5pi^2)/4), which is indeed -0.227359... Hope this helps!

Christopher
358409 (3) [Avatar] Offline
#5
Excellent, many thanks for the explanation, Christopher.

I had not spotted the significance of the actual position/length of the fraction bar (but should have!); I certainly was 'missing the obvious' as I stated in my first posting. I think I'll need to be doubly careful in future when transferring formulae from MathPrint examples to the TI-83, else I'll be tripped up again. Actually, this may serve as a justification to my OH for the 'need' to buy a TI-84 Plus C to replace my aging TI-83.

Thanks again for taking the trouble to explain my misunderstanding.

Regards, Chris
478082 (1) [Avatar] Offline
#6
Nice post