Answer:
Step-by-step explanation:
We are to show that 
<u>Proof:</u>
From trigonometry identity;


From trigonometry, 2sinAcosA = Sin2A

Also note that sin(B-C) = sinBcosC - cosBsinC
sin420cos140 - cos420sin140 = sin(420-140)
The resulting equation becomes;

= 
hope it helps you!!!!!!!!!
Answer: Eric: The 10 is the initial amount, the 1/2 is the decay factor or the rate at which it decreases, and the exponent w is the number of weeks it decreases by factor 1/2, or the time. Andrea, 1 is the initial amount, 0.2 is the decay factor or rate of decrease, w is time passed or number of weeks it's decayed by the factor.
Step-by-step explanation: Answer is explanation
Answer:
5 classes - 2 bass classes and 3 viola classes.
Step-by-step explanation:
Find the greatest common factor (GCF)
List the factors of 20 and 30:
20: 1, 2, 4, 5, 10, 20
30: 1, 2, 3, 5, 6, 10, 15, 30
The greatest factor that both numbers share is 10.
Therefore, there are 10 students in each class. So, she teaches 2 bass classes and 3 violas classes.
hope this helps! <3