(1 - tan²30°) / (1 + tan²30°) = কত?
সঠিক উত্তর: 1/2
ব্যাখ্যা: (1 - tan²30°) / (1 + tan²30°) = (1 - (tan 30°)²) / (1 + (tan 30°)²)
= (1 - (1/√3)²) / (1 + (1/√3)²)
= (1 - 1/3) / (1 + 1/3)
= ((3 - 1)/3) / ((3 + 1)/3)
= (2/3) / (4/3)
= 2/3 × 3/4
= 1/2