Riješi cosalpha

$$\cos \alpha$$

Diferenciraj u odnosu na α

$$-\sin(\alpha )$$

Koraci korištenja definicije derivacije

Za funkciju f\left(x\right) derivacija je limes od \frac{f\left(x+h\right)-f\left(x\right)}{h} pri čemu h teži 0, ako takav limes postoji.

$$\frac{\mathrm{d}}{\mathrm{d}\alpha }(\cos(\alpha ))=\left(\lim_{h\to 0}\frac{\cos(\alpha +h)-\cos(\alpha )}{h}\right)$$

Koristite formulu zbroja za kosinus.

$$\lim_{h\to 0}\frac{\cos(h+\alpha )-\cos(\alpha )}{h}$$

Izlučite \cos(\alpha ).

$$\lim_{h\to 0}\frac{\cos(\alpha )\left(\cos(h)-1\right)-\sin(\alpha )\sin(h)}{h}$$

Ponovno napišite limes.

$$\left(\lim_{h\to 0}\cos(\alpha )\right)\left(\lim_{h\to 0}\frac{\cos(h)-1}{h}\right)-\left(\lim_{h\to 0}\sin(\alpha )\right)\left(\lim_{h\to 0}\frac{\sin(h)}{h}\right)$$

Koristite činjenicu da je \alpha nepromjenljiv kad ograničenje računanja h stremi prema 0.

$$\cos(\alpha )\left(\lim_{h\to 0}\frac{\cos(h)-1}{h}\right)-\sin(\alpha )\left(\lim_{h\to 0}\frac{\sin(h)}{h}\right)$$

Limes od \lim_{\alpha \to 0}\frac{\sin(\alpha )}{\alpha } je 1.

$$\cos(\alpha )\left(\lim_{h\to 0}\frac{\cos(h)-1}{h}\right)-\sin(\alpha )$$

Da biste izračunali limes od \lim_{h\to 0}\frac{\cos(h)-1}{h}, prvo podijelite brojnik i nazivnik s \cos(h)+1.

$$\left(\lim_{h\to 0}\frac{\cos(h)-1}{h}\right)=\left(\lim_{h\to 0}\frac{\left(\cos(h)-1\right)\left(\cos(h)+1\right)}{h\left(\cos(h)+1\right)}\right)$$

Pomnožite \cos(h)+1 i \cos(h)-1.

$$\lim_{h\to 0}\frac{\left(\cos(h)\right)^{2}-1}{h\left(\cos(h)+1\right)}$$

Koristite pitagorejski identitet.

$$\lim_{h\to 0}-\frac{\left(\sin(h)\right)^{2}}{h\left(\cos(h)+1\right)}$$

Ponovno napišite limes.

$$\left(\lim_{h\to 0}-\frac{\sin(h)}{h}\right)\left(\lim_{h\to 0}\frac{\sin(h)}{\cos(h)+1}\right)$$

Limes od \lim_{\alpha \to 0}\frac{\sin(\alpha )}{\alpha } je 1.

$$-\left(\lim_{h\to 0}\frac{\sin(h)}{\cos(h)+1}\right)$$

Koristite činjenicu da je \frac{\sin(h)}{\cos(h)+1} nepromjenljiv pri 0.

$$\left(\lim_{h\to 0}\frac{\sin(h)}{\cos(h)+1}\right)=0$$

Supstituirajte vrijednost 0 u izrazu \cos(\alpha )\left(\lim_{h\to 0}\frac{\cos(h)-1}{h}\right)-\sin(\alpha ).

$$-\sin(\alpha )$$

Izračunaj

$$\cos(\alpha )$$