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Performing Sum to Product identity of trigonometric functions - Printable Version

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Performing Sum to Product identity of trigonometric functions - amindanial - 12-23-2024 06:19 AM

How can I perform sum to product identity of trigonometric functions on HP prime as follows:
sin(a)+sin(b) to get 2sin((a+b)/2)cos((a-b)/2).

RE: Performing Sum to Product identity of trigonometric functions - Jan 11 - 12-24-2024 03:15 PM

Now in HP Prime, you won't be able to perform this trigonometric identity. Maybe, in a future update, such a function will be added.

RE: Performing Sum to Product identity of trigonometric functions - amindanial - 12-24-2024 06:16 PM

(12-24-2024 03:15 PM)Jan 11 Wrote:  Now in HP Prime, you won't be able to perform this trigonometric identity. Maybe, in a future update, such a function will be added.

Thetefore, we have to inform the company about adding this function in the next update.

RE: Performing Sum to Product identity of trigonometric functions - Thomas Klemm - 12-24-2024 07:40 PM

Meanwhile with my HP-48GX I can define:
Code:
DIR
  EXPR 'SIN(U+V)+SIN(U-V)'
  ∑→Π
    « {
        'SIN(&A)+SIN(&B)'
        '2*SIN((&A+&B)/2)*COS((&A-&B)/2)'
      } ↓MATCH
    »
END

And then run:

EXPR ∑→Π DROP COLCT COLCT

This results in:

'2*SIN(U)*COS(V)'

RE: Performing Sum to Product identity of trigonometric functions - Albert Chan - 12-24-2024 09:00 PM

XCas has trigsimplify, but we had to nudge it to get what we want.

XCas> m := sin(a) + sin(b)
XCas> trigsimplify( m(a=c+g, b=c-g) ) (c=(a+b)/2, g=(a-b)/2)

2 * cos((a-b)/2) * sin((a+b)/2)

XCas> tlin( ans() )

sin(a) + sin(b)

RE: Performing Sum to Product identity of trigonometric functions - amindanial - 12-25-2024 05:11 AM

I think CAS engine of HP prime has to be upgraded.