Okay...

Given that:

sin cos

66 degrees 0.9135 0.4067

104 degrees 0.9703 -0.2419

213 degrees -0.5446 -0.8387

Find sin 81 degrees

Hint: Double, Difference

Apparently I don't understand the concept. Thanks! (Bow)

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- May 30th 2008, 02:58 PMaigiqinfTrig question I need to understand this tonight!
Okay...

Given that:

sin cos

66 degrees 0.9135 0.4067

104 degrees 0.9703 -0.2419

213 degrees -0.5446 -0.8387

Find sin 81 degrees

Hint: Double, Difference

Apparently I don't understand the concept. Thanks! (Bow) - May 30th 2008, 03:54 PMMathstud28
- May 30th 2008, 03:57 PMaigiqinf
- May 30th 2008, 04:11 PMsean.1986
- May 30th 2008, 04:14 PMSoroban
Hello, aigiqinf!

The hint refers to:

. . a Difference identity: .

. . two Double-Angle identities: .

Quote:

Given that: .

Find

Hint: Double, Difference

So: .

. . Since , we have: .

. . . . . . . . . . . . . . . .

Now substitute the values given in the table . . .

- May 30th 2008, 04:32 PMaigiqinf