3. Du vet att \( \boldsymbol{\operatorname { c o s }} \mathbf{v}=\mathbf{0 , 5 5} \). Beräkna vinkeln.

Find the exact value of \( \sin \left(-225^{\circ}\right) \)

Find the exact value of \( \sin \left(-225^{\circ}\right) \) Rewrite the expression \( \sin \left(-225^{\circ}\right) \) using the sum formula. Choose the correct answer below. A. \( \sin \left(-225^{\circ}\right)=\sin \left(180^{\circ}+45^{\circ}\right)=\left[\sin 180^{\circ} \sin 45^{\circ}+\cos 180^{\circ} \cos 45^{\circ}\right] \) B. \( \sin \left(-225^{\circ}\right)=-\sin \left(180^{\circ}+45^{\circ}\right)=-\left[\sin 180^{\circ} \cos 45^{\circ}-\cos 180^{\circ} \sin 45^{\circ}\right] \) C. \( \sin \left(-225^{\circ}\right)=-\sin \left(180^{\circ}+45^{\circ}\right)=-\left[\sin 180^{\circ} \cos 45^{\circ}+\cos 180^{\circ} \sin 45^{\circ}\right] \) D. \( \sin \left(-225^{\circ}\right)=\sin \left(180^{\circ}+45^{\circ}\right)=\left[\sin 180^{\circ} \sin 45^{\circ}-\cos 180^{\circ} \cos 45^{\circ}\right] \)

\( 2 \cos ( \frac { \pi } { 4 } - \frac { x } { 2 } ) \geq \sqrt { 3 } \)

Points \( A \) and \( B \) are separated by a lake. To find the distance between them, a surveyor locates a point \( C \) on land such than \( \angle C A B=51.4^{\circ} \). Find the distance across the lake from \( A \) to \( B \).

\( \frac { \cos \theta + \cos \beta } { \sin \theta - \sin \beta } = \frac { \sin \theta + \sin \beta } { \cos \beta - \cos \theta } \)