### 2D-3D

Two circles of equal size intersect and the centre of each circle is on the circumference of the other. What is the area of the intersection? Now imagine that the diagram represents two spheres of equal volume with the centre of each sphere on the surface of the other. What is the volume of intersection?

### Power Up

Show without recourse to any calculating aid that 7^{1/2} + 7^{1/3} + 7^{1/4} < 7 and 4^{1/2} + 4^{1/3} + 4^{1/4} > 4 . Sketch the graph of f(x) = x^{1/2} + x^{1/3} + x^{1/4} -x

### Fractional Calculus I

You can differentiate and integrate n times but what if n is not a whole number? This generalisation of calculus was introduced and discussed on askNRICH by some school students.

# Interactive Workout - Mathmo

##### Stage: 5 Short Challenge Level:

Our Mathmo interactive workout app for A-level fluency has had another makeover.

#### Release Notes:

Mathmo 0.9.3 has just been released at http://nrich.maths.org/mathmoApp

This release gives users much more control over question generation – allowing such things as question sharing, and predictable exercise content. It features a new cleaner user interface which should work on a wider range of browsers.

v0.9.3 should work in any HTML5 capable browser. Some answers have function plots which also require an SVG browser. This excludes IE6,7,8 but allows IE9+. Some Android browsers lack SVG.

The previously released version of Mathmo 0.5.0, is still available at http://nrich.maths.org/mobl/mathmo/mathmo.html