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What is sin 35° sin55° - cos35° cos55°

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joana1234 | Student, Grade 10 | eNoter

Posted August 22, 2012 at 3:00 PM via web

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What is sin 35° sin55° - cos35° cos55°

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted August 22, 2012 at 3:05 PM (Answer #1)

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The value of sin 35*sin 55 - cos 35*cos 55 has to be determined. Here it is not necessary to know the values of the sine or cosine of 35 or 55. Instead use the rule: sin a*sin b - cos a*cos b = -cos(a + b)

sin 35*sin 55 - cos 35*cos 55

=> -cos(35 + 55)

=> -cos 90

=> 0

The value of sin 35*sin 55 - cos 35*cos 55 = 0

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harikesh409 | Student , Grade 10 | eNoter

Posted December 22, 2012 at 9:15 AM (Answer #2)

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sin 35*sin 55 - cos 35*cos 55

=> -cos(35 + 55)

=> -cos 90

=> 0


Similarly sin(90)=1

sin35*sin55-cos35*cos55=1

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