Question

me ajudemmm por favor

Answer 1

1)

sen 105⁰= sen60⁰+sen45⁰

logo: sen(60⁰+45⁰)= senA×cosB + senB cosA ---> sen60⁰×cos45⁰ + sen 45⁰×cos60⁰

$\frac{ \sqrt{3} }{2} \times \frac{ \sqrt[]{2} }{2} + \frac{ \sqrt{2} }{2} \times \frac{1}{2 }$

portanto letra C

2)

cos 15⁰= cos60⁰- cos45⁰

logo: cosA×cosB + senA×senB (muda o sinal de acordo com a regra)

cos60⁰×cos45⁰+sen60⁰×sen45⁰

$\frac{1}{2} \times \frac{ \sqrt{2} }{2} + \frac{ \sqrt{3} }{2} \times \frac{ \sqrt{2} }{2}$

$\frac{ \sqrt{2} }{4 } + \frac{ \sqrt{6} }{4}$

3) cos75⁰= cos30⁰+cos45⁰

logo: cosA×cosB - senA×senB

cos30⁰×cos45⁰-sen30⁰×sen45⁰

$\frac{ \sqrt{3} }{2} \times \frac{ \sqrt{2} }{2} - \frac{1}{2} \times \frac{ \sqrt{2} }{2}$

$\frac{ \sqrt{6} }{4} - \frac{ \sqrt{2} }{4}$

4) tg15⁰= tg60⁰-tg45⁰

tgA+tgB/ 1 + (tgA×tgB)