What is the  x-component of vector  e⃗    of the figure in terms of the angle  θ  and the magnitude  e?

If we took E with angle theta given with X axis

then in this case vector has an adjacent component along x direction

now using geometry we can say

now we need to find its adjacent component along x axis

so we can write it as

now similarly in other way if we took angle phi

then we can say by geometry

now we need to find the opposite component of vector E

so here it is

this could be newton#'s law of cooling. the cooling curve is exponential