Answer:
sin(-255°) = √2 + √6/4
Step-by-step explanation:
We need to find sin -255°
We know that sin(-a) = - sin(a)
so, sin(-255°) = - sin 255°
We know that 180° + 75° = 255°
Now we can write sin(255°) = sin(180° + 75°)
We can use the identity:
sin(x+y) = sin(x) cos(y)+cos(x)sin(y)
x = 180° , y = 75°
Solving,
sin(x+y) = sin(x) cos(y)+cos(x)sin(y)
sin(180° + 75°) = sin(180°) cos(75°)+cos(180°)sin( 75°)
sin(180°) = 0
cos(75°) = √6 -√2/4
cos(180°) = -1
sin( 75°) = √2 + √6/4
Putting values,
sin(180° + 75°) = 0 (√6 -√2/4) + (-1)(√2 + √6/4)
sin(180° + 75°) = -(√2 + √6/4)
We know that sin(-255°) = -sin(255°)
Putting value of sin(255°)
sin(-255°) = -(-(√2 + √6/4))
sin(-255°) = √2 + √6/4
