Are these identities true for `0^(@) le A le 90^(@)` ? If not, for which values of A they are true ?
`sec^(2)A - tan^(2)A = 1`

Are these identities true for 0^(@) le A le 90^(@) ? If not, for which values of A they are true ? cosec^(2)A - cot^(2)A = 1

Are these identities true only for 0^(@) le A le 90 ^(@) ? If not ,for which other values of A they are true ? sec^(2) A-tan ^(2) A =1 " " cosec ^(2) A - cot ^(2) A=1

Find the values for tan 90^(@) ,cosec 90 ^(@) , sec 90 ^(@) and cot 90 ^(@)

If sec x + sec^(2) x = 1 then the value of tan^(8) x - tan^(4) x - 2 tan^(2) x +1 will be equal to 0

For which value of an acute angle theta ,(i) ( cos theta )/( 1-sin theta ) +(cos theta )/( 1+sin theta ) =4 is true ? For which value of 0^(@) le theta le 90 ^(@) , above equation is not defined?

If f(x) = cos x,0 le x le ( pi )/( 2) , then the real number 'c' of the mean value theorem is