Question

plz solve question 19​

Answer 1

secA = 1/cosA

=secA (1-sinA)(secA+tanA)

= [(1-sinA)(secA+tanA)]/cosA

multiplying (1-sinA) by 1/cosA

= (secA - tanA)(secA+tanA)

using identity

${a}^{2} - {b }^{2} = (a + b)(a - b)$

${ \sec(a) }^{2} - { \tan(a) }^{2} = 1$