No, the rock cycle does not have to start from the sedimentary rock
For most purposes there is no "beginning" to the rock cycle. Any rock can be weathered away and remade into sedimentary rock. Igneous rocks are sometimes depicted as the start of the rock cycle because the first rocks on Earth were igneous.
Three (3) rocks in the rock cycle are sedimentary, igneous, and metamorphic rock.
sedimentary rock
New rocks are formed, Igneous Rock, Sedimentary Rock, and Metamorphic Rock. It will take over a million years to complete the rock cycle, then it will start all over again.
The rock cycle describes how rocks are formed, and how they change to sedimentary rock, to metamorphic rock, to magma, to igneous rock, to sediment, and back to sedimentary rock.
It must erode into sediment and then be compressed to form sedimentary rock.
Because a sedimentary rock goes through the rock cycle.
yes it erodes
The rock cycle has to start at least with igneous rocks, some of which will be eruptive. We may assume that any 'sedimentary' rocks that arrived as meteors have all been metamorphosed, though there are counter instances. For example the Sudbury Meteor and mineral complex. (Canada).
sedimentary, igneous, and metamorphic
Igneous rock can weather and become sedimentary rock . Metamorphic rock can be melted in a volcano and become igneous rock. Igneous rock and sedimentary rock can be heated and pressurized to form metamorphic rock.
They all are part of the rock cycle