The ratio of the vertex angle to either of the base angles in an isosceles triangle is 5:2. Determine the measure of the vertex angle. Show how you arrived at your answer.

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the answer is c

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answer:  

step-by-step explanation:

here x represents the height of the pole,

and, the height of the shadow of the pole is 12 feet.

also, the angle of elevation from the top of the pole is 40°,

therefore,

by the low of sine,

which is the required equation for finding the value of x,