Question

Please help me with this question

Answer 1

Answer:

$\large\boxed{Q2.\ \cos\theta=\dfrac{3}{5}}\\\boxed{Q3.\ \sin(\alpha+\beta)=-\dfrac{13}{85}}$

Step-by-step explanation:

Q2.

$270^o$

Q3.

$180^o\alpha$

$270^o$

$\sin(\alpha+\beta)=\sin\alpha\cos\beta+\sin\beta\cos\alpha\\\\\text{Substitute:}\\\\\sin(\alpha+\beta)=\left(-\dfrac{15}{17}\right)\left(\dfrac{3}{5}\right)+\left(-\dfrac{4}{5}\right)\left(-\dfrac{8}{17}\right)\\\\=-\dfrac{45}{85}+\dfrac{32}{85}=-\dfrac{13}{85}$