Answer: Choice D
s^2 = 9^2 + 10^2 - 2(9)(10)cos(100)
==========================================================
Explanation:
Consider the pythaorean theorem
a^2 + b^2 = c^2
which is the same as saying
c^2 = a^2 + b^2
If we tack on "-2ab*cos(C)", then we end up with
c^2 = a^2 + b^2 - 2ab*cos(C)
which is one form of the law of cosines. The side c is opposite angle C, and the two are on opposite sides of the equation. The 'a's and 'b's are on the right side with the angle C.
Note if C = 90 degrees, then cos(C) = cos(90) = 0 which means the whole "-2ab*cos(C)" term goes to 0 and we'd be left with the pythagorean theorem again.
In this case, we replace c with s, replace 'a' with 9, replace b with 10, and C with 100.
Step-by-step explanation:
a)<PTR=90°(angles in a semicircle)
<RPT=50°
<PRT + <PTR + <RPT=180°(angles in a triangle)
<PRT=180-(90+50)
<PRT=40°
b)From ∆QTS
<TQS = <RTP =50°
<QTS=180-(50+28)
<QTS=102°
c)<QTR=180-(90+50)
<QTR=40°
<span>she wanted to buy 6 bottles.
the cost of 10 bottles was $12.
therefore we need to find the cost of one bottle and then find the cost for 6 bottles.
if 10 bottles cost - $ 12
then 1 bottle costs - $ 12 / 10 bottles
here we divided 12 by 10 , cost of 1 bottle is 12/10 to find the cost of 6 bottles we have to multiply by 6 .12 / 10 x 6
correct answer is therefore B. divide 12 by 10 and then mulitply by 6</span>
