private double resolveOffsetX(double radius, double viewY, Point center, int peekDistance) {
        final double opposite = Math.abs(center.y - viewY);
        final double radiusSquared = radius * radius;
        final double oppositeSquared = opposite * opposite;
        final double adjacentSideLength = Math.sqrt(radiusSquared - oppositeSquared);
        return adjacentSideLength - radius + peekDistance;
    }
Find the absolute horizontal distance by which a view at {@code viewY} should offset
to align with the circle {@code center} with {@code radius}, accounting for {@code peekDistance}.
turn/src/main/java/cdflynn/android/library/turn/TurnLayoutManager.java