Prove `tan 9^@. tan 21^@.tan 69^@.tan 81^@=1`

Prove tan 70^@=2tan 50^@+tan 20^@

Find the values of tan 9^@-tan 27^@-tan 63^@ + tan 81^@

tan10^@tan15^@tan75^@tan80^@ is

The value of tan1^@tan2^@tan3^@....tan89^@

Show that : tan 50^@=tan 40^@+2tan 10^@ .

Show that 1 -tan 10^@ -tan 35^@ = tan 10^@ tan 35^@

Find the value : tan5^@tan25^@tan30^@tan65^@tan85^@

Without taking the help of the table of trigonometric ratios,show that:(ii) tan10^@tan15^@tan75^@tan80^@=1

Show that:(i) tan48^@tan23^@tan42^@tan67^@=1

Prove that: tan 4° tan 43° tan 47° tan 86° = 1 .