This FDC is from Nov.2009 Songs issue illustrating "Humorous Songs"
The triangular stamp is from 2009 Minerals of Ukraine issue showing Sulfur.
Sulfur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant, multivalent non-metal. Sulfur, in its native form, is a bright yellow crystalline solid. In nature, it can be found as the pure element and as sulfide and sulfate minerals. It is an essential element for life and is found in two amino acids: cysteine and methionine. Its commercial uses are primarily in fertilizers, but it is also widely used in black gunpowder, matches, insecticides and fungicides. Elemental sulfur crystals are commonly sought after by mineral collectors for their brightly colored polyhedron shapes. In nonscientific contexts, it can also be referred to as brimstone.
The 3.75 UAH stamp is from 2009 Europa-Astronomy issue showing Meridian Circle.
The meridian circle, or transit circle, is an instrument for observing the time of stars passing the meridian, at the same time measuring its angular distance from the zenith. The idea of having an instrument (quadrant) fixed in the plane of the meridian occurred even to the ancient astronomers and is mentioned by Ptolemy, but it was not carried into practice until Tycho Brahe constructed a large meridian quadrant.
The combination of the telescope and meridian circle resulted in the transit telescope, which have since developed further and diverged.