Express cos(pi/6)cos(2pi/3)+sin(pi/6)sin(2pi/3) as a single trigonometric expression

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- January 2nd 2013, 09:56 AMalejandroUsin sum, difference, and double-angle identities
**Express cos(pi/6)cos(2pi/3)+sin(pi/6)sin(2pi/3) as a single trigonometric expression** - January 2nd 2013, 09:59 AMemakarovRe: Usin sum, difference, and double-angle identities
Why don't you follow the hint in the title of the thread?

- January 2nd 2013, 03:49 PMSorobanRe: Usin sum, difference, and double-angle identities
Hello, alejandro!

Quote:

Big hint: .