10 I think because 10+10+8+8=36 and 8 is 2 less than 10
P
=
12
5 this is what I got for that
We'll use the following properties of sine and cosine to prove this:



Then it's just a matter of filling it in...
sin20sin40 * sin60sin80 = 1/2(cos20 - cos60) * 1/2 (cos20 - cos140) =
1/8( cos40 + 1 - cos160 - cos120 - cos40 - cos80 + cos80 + cos200) =
1/8(1 - cos160 - cos120 + cos200) =
1/8(1 - cos160 - cos120 + cos160) =
1/8(1 - cos120 ) = 1/8( 1 + 1/2 ) = 3/16
Answer:
x = 21
Step-by-step explanation:
The 2 angles form a straight angle and are supplementary, thus
7x + 9 + 2x - 18 = 180, that is
9x - 9 = 180 ( add 9 to both sides )
9x = 189 ( divide both sides by 9 )
x = 21