### 1
df <- dat
d <- dist(df, method = "euclidean")
res.hc <- hclust(d, method = "ward.D2" )
cluster::coef.hclust(res.hc)
#0.9812443
res.agnes <- cluster::agnes(d, method = "ward")
res.agnes$ac
#0.9803578

### 2
df <- scale(dat)
d <- dist(df, method = "euclidean")
res.hc <- hclust(d, method = "ward.D2" )
cluster::coef.hclust(res.hc)
#0.9812493
res.agnes <- cluster::agnes(d, method = "ward")
res.agnes$ac
#0.9812493