tolong bantu no 3 sama 4 pake caranya yaa

no. 3 begitu caranya (pake rumus phytagoras)

3.AC=CB^2-AB^2
AC=15^2-12^2
AC=225 -144
AC=akar 81
AC=9
4.X=90-60-15
X=30-15
X=15 derajat