Math/physics question.?

Question

Fireworks at Memorial Park are fired at an angle of 82 degrees with the horizontal. The technician expects them to explode about 300 feet in the air 4.8 seconds after they are fired. Find the initial velocity of a shell fired from the ground.

Answer 1

y(4.8)=300=vi*sin(82)*4.8-16*4.8^2

vi=140.67 ft/sec

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