sums and differences of angles (1 Viewer)

[TheGreatest99.95]

had a brainfart, could someone please do this for me

Find the exact value of:
sin180cos60+cos180sin60

thanks in advance

 

[slyhunter]

 

[TheGreatest99.95]

how do you get the answer after sin(180+60)?

 

[slyhunter]

You work it out from the first line. Work out exact values for the 4 trig terms then simplify.

 

[artosis]

sin180 = 0

so sin180cos60 = 0
and cos180 = -1
and sin60 = root 3/2

therefore as slyhunter said; answer is negative root 3/ 2

 

[TheGreatest99.95]

cheeers

 

[Drongoski]

how do you get the answer after sin(180+60)?

given expression = sin(180+60) = -sin60 =

Angle 180+60 in 3rd quadrant.

 

[Drongoski]

sin180 = 0

so sin180cos60 = 0
and cos180 = -1
and sin60 = root 3/2

therefore as slyhunter said; answer is negative root 3/ 2

No no no - not the way to do it!