The image is a bit blurry, but I can make out some mathematical expressions. Here is what I can decipher:

1. It appears to involve trigonometric identities or expressions, specifically related to angles or trigonometric functions.
2. There are two expressions involving the angles $a$ and $b$: $\text{Expression 1: } \sin a \times \sin b = \text{something unclear}$ $\text{Expression 2: } \cos a \times \cos b = \text{something unclear}$
3. There is a notation that might be referring to an assignment or a step involving these trigonometric expressions.

Since the image is not entirely clear, could you please confirm the exact problem or expression you need help with? This will allow me to provide a more accurate solution.

Would you like to clarify any specific part or upload a clearer image?