private double resolveOffsetY(double radius, double viewX, Point center, int peekDistance) {
        final double adjacent = Math.abs(center.x - viewX);
        final double radiusSquared = radius * radius;
        final double adjacentSquared = adjacent * adjacent;
        final double oppositeSideLength = Math.sqrt(radiusSquared - adjacentSquared);
        return oppositeSideLength - radius + peekDistance;
    }
Find the absolute vertical distance by which a view at {@code viewX} should offset to
align with the circle {@code center} with {@code radius}, account for {@code peekDistance}.
turn/src/main/java/cdflynn/android/library/turn/TurnLayoutManager.java