Call a method of a class from a function within the class itself? C++

Question

I created the "checkCase4" function in my Tree class and within it I make 2 class methods (rotate_left and rotate_right).

Function:

void checkCase4(Node *child, Node *grand) {
 if (child == child->parent->right && child->parent == grand->left) {
  rotate_left(grand, child->parent, child);
  child = child->left;
 }
 else if (child == child->parent->left && child->parent == grand->right) {
  rotate_right(grand, child->parent, child);
  child = child->right;
 }
 checkCase5(child, child->parent->parent);
}

Method:

void Tree::rotate_right(Node *gr, Node *par, Node *ch){
...
}

And the following error returns to me:

rbt.cpp: In Function ːvoid checkCase4(Node*, Node*)':
rbt.cpp:32:44: error: ṃ rotate_left' was not declared in this Scope
rotate_left(grand, Child->Parent, Child);

rbt.cpp:36:45: error: ṃ rotate_right' was not declared in this Scope
rotate_right(grand, Child->Parent, Child);

If anyone can help me, I’d really appreciate it.