is equal to

• -1

• 1

• 0

• None of these

 is equal to 

• 
• 
• 

• 1

A.

We have,  
               
               
                
               
              
                               
                 

   is

• 2 cosec A

• 2 sec A

• 2 sin A

• 2 cos A

A.

2 cosec A

(1 + sec 20° + cot 70°)(1 - cosec 20° + tan70°) is equal to

• 0

• 1

• 2

• 3

C.

2

a, b, c are the lengths of three sides of a triangle ABC. If a, b, c are related by the relation a² + b² + c² = ab + bc + ca, then the value of sin²A+ sin²B + sin²C is

• 
• 
• 
• 

D.

     
Δ ABC is an equilateral triangle.