Question

Sin 35 sin 55 - cos 35 cos 55 =??

Answer 1

Answer:

Sin 35 sin 55 - cos 35 cos 55 =0

Step-by-step explanation:

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

Answer 2

Answer:

$Value \:of \:\\sin35sin55-cos35cos55\\=0$

Step-by-step explanation:

$We\: know \: that\\\boxed {cosAcosB-sinAsinB=cos(A+B)}$

Now,

$sin35sin55-cos35cos55\\=-(cos35cos55-sin35sin55)\\=-[cos(35+55)]\\=-cos90\degree\\=0$

Therefore,

$Value \:of \:\\sin35sin55-cos35cos55\\=0$

•••♪