1.

Find the value of 3 \sin 15^{\circ}-4 \sin ^{3} 15^{\circ} -

Answer»

sin 15 = sin(45 - 30)= sin45 cos30 - cos45 sin30= ½√2(½√3) - ½√2(½)= ¼(√6 - √2)maka3 sin15 - 4 sin³15 = 3(¼(√6 - √2)) - 4(¼(√6 - √2))³= ¾(√3√2 - √2) - (1/16)(√3√2 - √2)³= (√3 - 1)¾√2 - (3√3 - 5)¼√2

…3(√3 - 1)√2 - (3√3 - 5)√2= ------------------------------------……………….4

= ½√2

Please solve



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