If A + B = 90°, then what is the value of $\sqrt{\mathrm{sinA} \mathrm{secB} - \mathrm{sinA} \mathrm{cosB} }$?

Given A + B = 90°
$\Rightarrow \sqrt{\sin \mathrm{A} \sec \mathrm{B} - \mathrm{sinA} \mathrm{cosB}} = \sqrt{\sin \mathrm{A} \sec \left({90}^{\mathrm{o}} - \mathrm{A}\right) - \mathrm{sinA} \cos \left({90}^{\mathrm{o}} - \mathrm{A}\right)}$

$\Rightarrow \sqrt{\mathrm{sinA}.\mathrm{cosecA} - \mathrm{sinA}.\mathrm{sinA}} = \sqrt{1 - {\sin }^2\mathrm{A}} =\sqrt{{\cos }^2\mathrm{A}} =\mathrm{cosA}$