Phần 1
Câu 2 : \(...T=2sin\left(\dfrac{\pi}{2}-x\right)+3cos\left(\pi-x\right)\)
\(=2cosx-3cosx=-cosx=kcosx\Rightarrow k=-1\)
Câu 3 : \(...S=\dfrac{sin\left(\dfrac{\pi}{2}-x\right)-2cos\left(\pi-x\right)}{cos\left(\dfrac{\pi}{2}-x\right)}=\dfrac{cosx+2cosx}{sinx}\)
\(=3cotx=kcotx\Rightarrow k=3\)
Câu 5 : \(...A=tan\left(\dfrac{\pi}{2}-x\right)+2cot\left(\pi-x\right)=cotx-2cotx=-cotx=kcotx\Rightarrow k=-1\)
Câu 6 :
\(...B=\dfrac{2sinx+cos\left(\dfrac{\pi}{2}-x\right)}{sin\left(\dfrac{\pi}{2}-x\right)}=\dfrac{2sinx+sinx}{cosx}=3tanx=ktanx\Rightarrow k=3\)
Câu 7 :
\(...\Leftrightarrow A=\dfrac{\dfrac{3sin\alpha}{cos\alpha}+\dfrac{4cos\alpha}{cos\alpha}}{\dfrac{2sin\alpha}{cos\alpha}-\dfrac{5cos\alpha}{cos\alpha}}=\dfrac{3tan\alpha+4}{2tan\alpha-5}\)
\(cot\alpha=\dfrac{1}{3}\Rightarrow tan\alpha=3\)
\(\Rightarrow A=\dfrac{3.3+4}{2.3-5}=13\)
