Question

Cosec² 72º - tan² 18º = 1​

Answer 1

cosec^2(72)-tan^2 (18)=1

Cosec^2 (90-18)-tan^2 (90-72)=1

Sec^2 (18)-tan^2 (18)=1

Hence,we know that [sec^2A-tan^2A=1],we get

Sec^2 (18)-tan^2 (18)=1

HENCE PROVED