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;
= 
Use the pythagorean therom. 12 squared + 3 squared = x squared
So the answer is 12.4 feet
Answer: 1 2/3
Step-by-step explanation:
The expression to find the perimeter of a rectangle is 2(length + width)
Length = 1/3
Width = 1/2
Perimeter = 2( 1/3 + 1/2)
Lowest common factor = 6
Perimeter = 2 [ (2 + 3) / 6]
Perimeter = 2 [ 5/6]
Perimeter = 10/6
Perimeter = 1 4/6 = 1 2/3
