Question

find the value of cos - 765 degree​

Answer 1

Question :-

• Find the value of cos (- 765°)

Answer

To Find : -

• The value of cos (- 765°)

Formula used :-

$\bf \:cos( - x) = cosx$

$\bf \:In \: first \: quadrant \: cosx > 0$

Solution :-

$\bf \:Consider \: cos( - 765°)$

$\bf\implies \:cos765°$

$\bf\implies \:cos(90° \times 8 + 45°)$

This implies, cosx lies in first quadrant and its a even multiple of 90°, there is no change in Trigonometric Ratio, so we get

$\bf\implies \:cos45°$

$\bf\implies \:\dfrac{1}{ \sqrt{2} }$

$\bf\implies \:cos( - 765°) = \dfrac{1}{ \sqrt{2} }$

__________________________________________