### Answers (61)

 23 What would have been our number system if humans had more than 10 fingers? Try to solve this puzzle. 22 Solve $\cos^2x-\sin^2x= 1$ 15 How to find the value of $\sin{\dfrac{\pi}{14}}+6\sin^2{\dfrac{\pi}{14}}-8\sin^4{\dfrac{\pi}{14}}$ 10 Trying to find a function whose derivative is $\cfrac{4x^3}{x^4+1}$ any ideas? 9 How can I prove that $xy\leq x^2+y^2$?

### Reputation (2,474)

This user has no recent positive reputation changes

### Questions (7)

 11 How to prove $\cos\left(\pi\over7\right)-\cos\left({2\pi}\over7\right)+\cos\left({3\pi}\over7\right)=\cos\left({\pi}\over3 \right)$ 3 Angles between vectors using a non-standard inner product 2 How do you determine if a function is nonelementary antiderivative [duplicate] 1 Determine number of squares in progressively decreasing size that can be carved out of a rectangle 0 Concept: Multiplying a vector by a scalar quantity

### Tags (48)

 65 algebra-precalculus × 16 14 calculus × 6 54 trigonometry × 7 10 real-analysis × 4 31 puzzle × 3 9 inequality 31 number-systems × 3 8 geometry × 7 18 derivatives × 4 8 quadratics

### Bookmarks (1)

 239 The Integral that Stumped Feynman?

### Accounts (30)

 Stack Overflow 55,194 rep 1414 gold badges101101 silver badges185185 bronze badges Code Golf 2,881 rep 99 silver badges2525 bronze badges Mathematics 2,474 rep 1111 silver badges1919 bronze badges Puzzling 1,790 rep 99 silver badges1818 bronze badges The Workplace 479 rep 33 silver badges66 bronze badges

### Badges (17)

 Yearling × 9 Nice Answer × 5 Lifejacket Explainer Nice Question Custodian Caucus × 2 Mortarboard Enlightened Critic

### Active bounties (0)

This user has no active bounties

### Votes cast (19)

all time   by type
15 up 12 question
4 down 7 answer