Question

tan1°tan11°tan21°tan69°tan75°tan89° = 1 proove that

Answer 1

i think instead of tan 75 it is tan 79

Step-by-step explanation:

tan 1 tan 11 tan 21 tan 69 tan 79 tan 89= 1

tan 1 tan 89 tan 21 tan 69 tan 11 tan 79 (you can rearrange the terms as it is multiplication in between)

=tan (90-1) tan 89 tan(90-21) tan 69 tan (90-11) tan 79

= cot 89 tan 89 cot 69 tan 69 tan 79 cot 79

= 1  

∴ proved