Question

Prove the trigonometric identities
Please prove the following trigonometric identities by using formula and table values​

Answer 1

Step-by-step explanation:

I will solve 21 problem

sin a + cos a = x --------->1

sin a - cos a = y -------->2

squaring on both sides and add

(sin^2(a)+cos^2(a)+2sinacosa+ sin^2(a)+cos^2(a)-2sinacosa) =x^2+y^2

solving this

1+1=x^2+y^2. (sin^2(a)+cos^2(a)=1)

.: x^2+y^2 = 2