Sec x -tan x sin x =1/secx

Help me prove it

What are the measures of ∠a, ∠b, ∠c and ∠d? explain how to find each of the angle measure.

Construct the graph that models the given situation

The sum of the first eight terms of an arithmetic progression is 9m + 14. the fifth term of the06 progression is 2m - 6, where m is a constant.given that the first term of the progression is 26,find the value of the common difference, d and thevalue of m.