Since it's a right triangle, we know that we can use SOHCAHTOA for this.
To find a, we know it's the side adjacent to the angle, and our other given value is the opposite side, 18. We can use TOA, (Tangent of 15) x 18, or 18tan15
this is 15.1, so you can now use this concept to find b (hypotenuse), then add that all up to get the perimiter!
Let me know if this helps!
