From the meaning of the question, the sine value of acute angle α is 2 (root number 5)/5, and the cosine value of obtuse angle β is -3 (root number 10)/ 10, so the cosine value of acute angle α is

(root number 5)/5, and the sine value of obtuse angle β is (root number 10)/ 10. According to the sine formula, sin(α-)=sinα*cosβ-cosα*sinβ.

Substitute the number, sin(α-β)=-7 times the root number 2/ 10.

(2): Similarly, according to sine sum formula and number, sin(α+β)= negative root sign 2/2.

Because acute angle α and obtuse angle β, α+β are located in the third quadrant, α+β=5π/4.