Every Angle

Who it is for

• Adults who want the geometry, algebra and trig they missed, taught through a job that pays them back the same month: every idea is used on the house the week you learn it.
• Households that want to secure the house without overpaying: check an installer's quote line by line, or do the low-voltage job yourself.
• A gift for a teen of 13 or older, with an adult alongside for the ladder and the drill.
• Homeschool and maker families who want a project with a number at the end of every step.

Not for: exam-syllabus coverage or proofs, or anyone who wants the plan without the arithmetic. It is never a substitute for an electrician, a roofer, a lawyer or the data-protection regulator where the book says so.

What you build: Measure, Cover, Price

One house and plot, surveyed to scale; a coverage plan of cameras, a doorbell camera and motion lights; a priced parts list used two ways. Every chapter hands it one number.

• The measured plan: a 15 × 30 m plot (450 m²) and a 10 × 8 m house drawn at 1 : 100; eaves 5.4 m by shadow, the back-garden tree 13.75 m by a paper clinometer.
• The coverage plan: a typical 4 MP camera identifies a face (250 px/m) out to 4.30 m; mounted at 2.7 m and tilted 20° it leaves a 2.56 m blind spot underneath. The first plan left the west passage about 90% blind; 5 cameras and the doorbell leave no blind stretch on the four approach routes.
• Cable and storage: 74.0 m of cable, the longest run 22.4 m against the 100 m limit; 18.5 days on a 2 TB drive.
• The price, two ways: a fair quote of about 2,485.59 against an illustrative installer's 2,780.00, or a DIY bill of 1,357.80. These are worked examples at illustrative November 2026 prices, with a column for your own numbers, not promises.

The game: every chapter ends with Call It (write the number before you measure) and Check It (the gap scores 3, 2, 1 or 0). A Quest Map tracks the eleven stations, the night walk earns a Coverage Score of Gold, Silver or Bronze, and a Trophy page holds the result. Twelve more home jobs are measured and priced at the end.

The house was worked out on paper from published figures, not surveyed by us: measure your own and walk your own plot at night. The book was written in collaboration with AI tools and reviewed by the author. Its numbers are checked by a verification program, and its figures are drawn by the same program, but mistakes may remain: see corrections & errata. Ladders at 4 : 1 and never on the roof; PoE and 12 V wiring only, mains work is an electrician's; cameras respect the neighbors' privacy. Coverage is a plan, not a promise.