q = int(input().strip())
def parallel(m1, m2):
    return m1[0]*m2[1]==m1[1]*m2[0]
def orthogonal(m1, m2):
    return m1[0]*m2[0]==-m1[1]*m2[1]
def line(m, P):
    return [m, m[1]*P[1]-m[0]*P[0],  m[1]] # slope, y-intercept-num, y-intercept-den
def onLine(P, L):
    dx=L[0][1]
    dy=L[0][0]
    return dx*P[1]==dy*P[0]+L[1]
def onSomeLine(P, lines):
    l=0
    for l in range(4):
        if onLine(P, lines[l]):
            return (l+1)
    return 0

for _ in range(q):
    checkRect=1
    n = int(input().strip())
    x=y=[]
    for _ in range(n):
        xnum, ynum = input().strip().split()
        xnum, ynum = [int(xnum), int(ynum)]
        x.append(xnum)
        y.append(ynum)
    if n==3 or len(set(x))<3 or len(set(y))<3: # includes (# pts)<=3 and vertical/horizontal sides
        checkRect=1
    else:
        # form L1 with first two points
        # check if 
        xmin = min(x)
        ix1 = x.index(xmin)
        A=[x[ix1],y[ix1]]
        xmax = max(x)
        ix2=x.index(xmax)
        C=[x[ix2],y[ix2]]
        ymin = min(y)
        iy1=y.index(ymin)
        B=[x[iy1], y[iy1]]
        ymax = max(y)
        iy2=y.index(ymax)
        D=[x[iy2], y[iy2]]
        # Calculate Slopes [dy, dx]
        if A==B or B==C or C==D or D==A:
            checkRect=0
        else:            
            #print(A,B,C,D)
            m1=[A[1]-D[1], A[0]-D[0]]
            m2=[A[1]-B[1], A[0]-B[0]]
            m3=[C[1]-B[1], C[0]-B[0]]
            m4=[C[1]-D[1], C[0]-D[0]]
            if orthogonal(m1, m2) and orthogonal(m2, m3) and orthogonal(m3, m4):
                L1=line(m1, A)
                L2=line(m2, B)
                L3=line(m3, C)
                L4=line(m4, D)

                for P in [[x[i], y[i]] for i in range(n) if not [x[i], y[i]] in [A, B, C, D]]:
                    P=[x[i], y[i]]
                    # now check that each point belongs to one of the lines
                    lines=[L1, L2, L3, L4]
                    l=onSomeLine(P, lines)
                    if l==0:
                        checkRect=0
                        break
                    else: # Then check if P is in between                    
                        pts = [[D, A], [A, B], [B, C], [C, D]]
                        m, b, dx = lines[l-1]
                        S, T = pts[l-1]
                        t = (P[0]-T[0])/float(S[0]-T[0])
                        #print("t=", t)
                        if t<0 or t>1:
                            checkRect=0
                            break
                checkRect=1                       

            else:
                print("HERE")
                checkRect=0
    if checkRect==0:
        print("NO")
    else:
        print("YES")