Answer:
a=7
Step-by-step explanation:
The image is rendered and attached below.
Triangle WXY is an Isosceles right triangle, since WX=XY.
First, we determine the length of WY using Pythagoras Theorem.
Since triangle WXY is Isosceles, 
Therefore:
Triangle WYZ is a right triangle with WZ as the hypothenuse.
Applying Pythagoras Theorem
21.6 ÷ 0.4 = 54 times for green
21.6 ÷ 0.6 = 36 times for purple
Together, 90 beads. Separately, 54 green and 36 purple.
The resultant velocity of the plane is the sum of the two velocity vectors which are perpendicular to each other. See the attached figure.
The magnitude of the resultant velocity is
.
The approximate value of the actual velocity of the plane is 
. Correct choice is (D).
28÷4=7
so 7<span>deliveries per hour</span>
<span>sin(angle)=<span><span>opposite leg/</span><span>hypotenuse</span></span></span>
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</span></span></span>
<span><span><span> sin(20) = 10/ hypotenuse</span></span></span>
<span><span><span>hypotenuse = 10/sin(20) = 29.238 ( round off as necessary)</span></span></span>
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