Question

Trigonometry !!!!

○Find the value of cos 75°?​
○Find the value of sin 135° ?​
○$= \frac{ { \sin }^{2}48 }{ { \cos }^{2}48 } + 1 = ?$


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Answer 1

trignometery

Step-by-step explanation:

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Answer 2

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Solution 1❇

= cos 75°

= cos (45°+30°)

= cos 45°. cos 39° - sin45° . sin30°

= $\displaystyle\frac {1}{\sqrt{2}}.\displaystyle\frac {\sqrt {3}}{2}-\displaystyle\frac {1}{\sqrt{2}}.\displaystyle\frac {1}{2}$

=$\displaystyle\frac {\sqrt {3}}{2\sqrt{2}}-\displaystyle\frac {1}{2\sqrt{2}}$

=$\displaystyle\frac {\sqrt {3}-1}{2\sqrt{2}}$

Solution 2❇

= sin 135°

= sin (90+45°)

= sin 90.cos45+cos90.sin45

= $1 × \displaystyle\frac {1}{\sqrt{2}}+ 0×\displaystyle\frac {1}{\sqrt{2}}$

=$\displaystyle\frac {1}{\sqrt{2}}$

Solution 3❇

$= \frac{ { \sin }^{2}48 }{ { \cos }^{2}48 } + 1 = ?$

$= { \tan}^{2} 48 + 1$

$={\sec}^{2}\:48°$

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