Step 1:
First, we rewrite the integral by splitting the fraction into two parts:
$$\int_{0}^{x / 4} \frac{1+\cos ^{2} \theta}{\cos ^{2} \theta} d \theta = \int_{0}^{x / 4} \frac{1}{\cos ^{2} \theta} d \theta + \int_{0}^{x / 4} \frac{\cos ^{2} \theta}{\cos ^{2}
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