Question

if tan A + cot A is equal to 5 find the value of 10 square A + cos square A....plz need full answer

Answer 1

tanA +cotA = 5 (given) 
(tanA + cotA)^2 = (5)^2 (squaring both sides) 
tan^2A + cot^2A + 2× tanA×cotA = 25 [ (a+b)^2 = a^2+b^2+2ab ] 
tan^2A + cot^2A + 2×1 = 25 (tanA×cotA = tanA×1/tanA = 1 ) 
tan^2A + cot^2A = 25 - 2 = 23