Verify the identity.

tan(x+(pi/2)) = -cot x

Acar started driving from city a to city b, distance between which is 620 miles, at a rate of 60 mph. two hours later a truck left city b and started moving towards city a at a rate of 40 mph. how many hours after the truck's departure will the two meet?

Write the equations in logarithmic form 9^4=6,561

The weight of a full steel bead tire is approximately 800 grams, while a fighter wheel weighs only 700 grams. what is the weight of each tire in pounds?