Question

sin square 70 + cos square 70



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Answer 1

Answer:

Hence the answer is  1 .

Step-by-step explanation:

We will use two identities over here. They are,

sinx=cos(90−x)  or  cosx=sin(90−x) ..(1)

The above identity is the very reason why the two functions are called ‘sine’ and ‘COsine’ . Highlighted the ‘CO’ over here because this ‘CO’ stands for ‘Complementary’. Or in other words if you put some input  x  in the function  sinx  then  cosx  will give you the same output for the complementary input  90−x .

sin2x+cos2x=1 ..(2)

Now you see,

sin70=cos(90−70)=cos20  by (1)

Hence,  sin270+sin220=cos220+sin220=1  by (2)

Hence the answer is  1 .