Question

suggest a indirect method for measure the height of tree on a sunny day

Answer 1

Firstly, find the length of the shadow of the tree and calculate the elevation angle between the sun and earth from that point.

Now, use the trigonometric ratio tanӨ = height of tree/ height of shadow

where, Ө ​= angle of elevation.

Answer 2

At a secret location somewhere in northern California, a tree named Hyperion has been measured at a world record height of 379.3 feet (115.61m)![1] Believe it or not, the measurement was made with an extra long tape measure, but there are much easier methods you can try yourself. While you won't be accurate to the exact inch or centimeter, these methods will give you a good approximation, and works on any tall object. Telephone poles, buildings, or magic beanstalks: as long as you can see the top, you can measure it.