# How do you perform multiplication and use the fundamental identities to simplify (3-3sinx)(3+3sinx)?

Answer $= 9 {\cos}^{2} x$
$\left(a + b\right) \left(a - b\right) = {a}^{2} - {b}^{2}$
Here, $a = 3$ & $b = 3 \sin x$
$\therefore \left(3 - 3 \sin x\right) \left(3 + 3 \sin x\right) = \left({3}^{2} - {3}^{2} {\sin}^{2} x\right) = 9 - 9 {\sin}^{2} x$
$= 9 \left(1 - {\sin}^{2} x\right) = 9 {\cos}^{2} x$
{"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 6, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0}