Answer:
Step-by-step explanation:
To prove sin(a+b)*sin(a-b)=cos^2b-cos^2a
we simplify the left side sin(a+b)*sin(a-b) first
sin(a+b) = sin a cos b + cos a sin b
sin(a-b) = sin a cos b - cos a sin b
sin(a+b)*sin(a-b) = (sin a cos b + cos a sin b) x (sin a cos b -cos a sin b)
sin a cos b((sin a cos b + cos a sin b) - cos a sin b (sin a cos b + cos a sin b)
open the bracket
sin a cos b(sin a cos b) + sin a cos b(cos a sin b) -cos a sin b (sin a cos b)+ cos a sin b ( cos a sin b)
sin²a cos²b + sin a cos b cos a sin b - cos a sin b sin a cos b + cos²a sin²b
sin²a cos²b + 0 + cos²a sin²b
sin²a cos²b + cos²a sin²b
- sin²a = 1-cos² a
- sin²b = 1-cos² b
(1-cos² a)cos² b - cos² a(1-cos² b)
= cos² b - cos² a cos² b - cos² a +cos² a cos² b
cos² b - cos² a - cos² a cos² b + cos² a cos² b = cos² b - cos² a + 0
cos² b - cos² a
left hand side equals right hand side
1 case=8 boxes of cookies and we have 160 boxes
160/8=20
we will have 20 cases
Answer:
1) D
3) B
4) F
6) G
Step-by-step explanation:
The guy who did this first is right.
The activity described is an Observational Study. The explanatory variable was the design of the surrounding merchandise.
<h3>Research and Realism</h3>
The exercise is an observational study because the researcher does not interfere with the subjects.
B) The study does not suffer from a lack of realism. The people were recruited randomly and were not told what to observe, rather, they were questioned later on what they had observed.
Realism in research refers to the concept that what occurs in the mind are tangible. These tangible occurrences may modify behavior and the factors that trigger such behaviors can be observed and identified by the use of qualitative means.
See the link below for more about Observational Studies:
Observational Studies:brainly.com/question/1051685
See the link below for more about Realism:
brainly.com/question/26483670