cos αsin β=ncos αsin β=n end cos αcos β=m,cos αcos β=m, then the velue of cos2βcos2β is?

• ক m2+3n2+3m2+3n2+3
• খ n2m2+n2 ✅ সঠিক উত্তর
• গ m2−3n2−4m2−3n2−4
• ঘ m2−1n2−1m2−1n2−1