If the angle of elevation of the Sun changes from 30° to 45°, the length of the shadow of a pillar decreases by 20 meters . The height of the pillar is:

If \(tan\space \theta-cot\space \theta = cosec\space \theta\), \(0^0<\theta<90^0\), then what is the value of \({2tan\space \theta-cos\space \theta\over \sqrt3cot\space \theta+sec\space \theta}\) ?

A completes 20% of a work in 5 days and B completes one-third of the work in 5 days. They began the work together but B leaves after 3 days. The total number of days needed for completion of the work is:

A tradesman gives 4% discount on the marked price and gives 1 article free for buying every 15 articles and thus gains 35%. The marked price is increased above the cost price by