Proof: cos(a+b) = (cos a)(cos b)-(sin a)(sin b)
Khan Academy
•
July 11, 2008
Khan Academy
View ChannelAbout
No channel description available.
Latest Posts
Enhance Your Learning Journey
Loading...
Microscope Science Kit 100X/400X/1200X Magnification Scientific Microscope with Slides Educational STEM Students Beginners White
(0)
$24.89
FREE delivery Jun 20 - Jul 14 Only 1 left in stock.
Loading...
Microscope Science Kit 100X/400X/1200X Magnification Scientific Microscope with Slides Educational STEM Students Beginners Blue
(0)
$24.89
FREE delivery Jun 20 - Jul 14 Only 1 left in stock.
Loading...
Graphics Drawing Tablet,LCD Writing Tablet,Electronic Writing&Drawing Board Doodle Board,Handwriting Paper Drawing Tablet with Faux Leather Case Gift for Kids and Adults at(Black (with Leather case))
(9)
$29.72
FREE delivery Tue, Jun 3 on your first order
Loading...
Joyzan Kraft Pillow Boxes, Paper Candy Favor Boxes Small Mini Party Gift Treat Wedding Packaging Brown Wrapping Supplies Box for Chocolate Bakery Baby Shower Birthday Soap Jewelry Graduation 50pcs
(1)
$13.49
FREE delivery Tue, Jun 3 on your first order
Loading...
Large Framed Abstract Wall Art - Black and White Wall Decor 40cmx60cm Set of 3 Modern Geometric Wall Paintings Minimalist Dots Lines Prints Canvas Pictures for Living Room Bedroom Bathroom
(4)
$98.99
PrimeFREE delivery Tue, Jun 3
Loading...
Mathematics for Finance: An Introduction to Financial Engineering
(73)
$42.93$29.51
Prime$6.79 delivery Wed, Jun 4 Arrives before Father's Day
Loading...
DIGOBAY World Map Jigsaw Puzzle for Kids 4-8, 70 Piece Globe Large Round Floor Puzzles for Kids Ages 3-5 Toddler Puzzle Geography Games Educational Toys Birthday Gifts for Children
(1,103)
$36.99
PrimeFREE delivery Thu, Jun 5
50+ bought in past month
Loading...
Weelikeit 2025 Kids Tablet, 7 inch Toddler Tablet for Kids 64GB Kids Edition Android Tablet with Parental Control, WiFi, GMS, Dual Camera, Educational Games Preinstalled, for Kids Ages 3-14 (Blue)
(53)
$68.39$64.97
PrimeFREE delivery Thu, Jun 5
50+ bought in past month
Loading...
Osmo Little Genius Sticks & Rings-2 Educational Learning Games -Ages 3-5-Imagination,Letter Formation & Creativity-For iPad Or Fire Tablet -STEM Toy,Boy & Girl(Osmo Base Required - Amazon Exclusive)
(1,607)
$37.99
PrimeFREE delivery Wed, Jun 4
Loading...
Osmo Super Studio Disney Mickey Mouse & Friends - Ages 5-11 - Learn to Draw - For iPad or Fire Tablet Educational Learning Games - STEM Toy Gifts Boy & Girl-Ages 5 6 7 8 9 10 11(Osmo Base Required)
(1,987)
$27.99
FREE delivery Wed, Jun 4 on your first order
Loading...
Ukulele Primer Book for Beginners: with Online Video Access
(2,624)
$12.99$11.36
FREE delivery Tue, Jun 3 on your first order
Loading...
McAfee Total Protection 2025 | 10 Device | Cybersecurity Software Includes Antivirus, Secure VPN, Password Manager, Dark Web Monitoring | 1 Year Subscription with Auto-Renewal|| Online Code
(35)
$29.99
Available now
Loading...
McAfee+ Premium Family 2025 Unlimited Devices | All-In-One Cybersecurity Software includes Unlimited VPN, Identity Monitoring, and Antivirus | 1 Year Subscription with Auto-Renewal| Online Code
(156)
$44.99
Available now
Loading...
McAfee+ Premium Individual 2025 Unlimited Devices | All-In-One Cybersecurity Software includes Unlimited VPN, Identity Monitoring, and Antivirus | 1 Year Subscription with Auto-Renewal| Online Code
(156)
$34.99
Available now
Loading...
3D Illusion Lighting LED Anime Lamp Desk RGB 16 Colors Change Remote Kids Bedroom Night Light for Boys
(57)
$19.99
FREE delivery Tue, Jun 3 on your first order
Loading...
Jesus Cross 3D Night Light Desk Table Lamps,Warm Colors LED Wooden Lighting for Holiday Gifts
(824)
$24.99
FREE delivery Tue, Jun 3 on your first order
Loading...
Desktop Glass Whiteboard with Reversible Wood Stand, Small White Board, Mini Dry Erase Whiteboard Easel for Desk, Reusable Desk Notepad 9.5"x6.7" for Home, Office, Accessories Included, Yeoux
(869)
$28.99
FREE delivery Tue, Jun 3 on your first order
50+ bought in past month
Loading...
STAMTECH Custom Golf Ball Stamp - Personalized Golf Ball Stamp Markers with Monogram to Indentify Golf Balls, Add a Personal Touch to Your Golf Game
(39)
$20.99
FREE delivery Jun 12 - 25
50+ bought in past month
Loading...
MoKo Magnetic Dry Erase Calendar for Refrigerator, 16.73"x12" Dry Erase Monthly Schedule Planner and Grocery Shopping List with 8 Markers for Kitchen Fridge and White Board - Black
(5,529)
$17.86
FREE delivery Tue, Jun 3 on your first order
Loading...
Shuttle Art Permanent Markers, 30 Pack Black Permanent Marker set,Fine Point, Works on Plastic,Wood,Stone,Metal and Glass for Doodling, Marking…
(4,054)
$21.99
FREE delivery Tue, Jun 3 on your first order
600+ bought in past month
Loading...
DOMISL Black Edible Markers for Cookies 3 Pcs Food Coloring Pens, Food Grade Gourmet Writers with Fine Thick Tip, Baking Paintbrush for DIY Fondant Cakes Frosting Easter Eggs Party Decorating Drawing Writing
(70)
$8.99
FREE delivery Tue, Jun 3 on your first order
50+ bought in past month
Loading...
Mamol Privacy Screen MacBook Pro 14 Inch (2021-2024, M1, M2, M3), Magnetic Removable Anti Blue Light Glare Filter 14in Privacy Screen Protector for Apple Mac Pro 14.2'' Laptop, Model: A2442/ A2779
(316)
$38.99
PrimeFREE delivery Fri, Jun 6
Loading...
Wireless Bluetooth Mouse for Apple iPad iPhone MacBook Android Samsung Tablet Phone Dual-Mode Rechargeable 2.4G Portable Computer Mice for Windows Laptop Notebook PC Mac Desktop USB Receiver (Black)
(1,684)
$15.99
FREE delivery Fri, Jun 6 on your first order
50+ bought in past month
Loading...
iClever BK10 Bluetooth Keyboard, Multi-Device Wireless Keyboard with Numeric Keypad, Rechargeable Ultra Slim Compact Portable Keyboard for Mac, iPad, PC, Desktop, Laptop, iOS, Android, Windows
(11,683)
$46.99
PrimeFREE delivery Fri, Jun 6
100+ bought in past month
Loading...
Plugable Thunderbolt 4 Hub | 60W Laptop Charging | 3X Thunderbolt 4 Ports | Dual 4K/Single 8K Displays | USB4 Compatibility - TBT4-HUB3C
(202)
$139.95
PrimeFREE delivery Fri, Jun 6
50+ bought in past month
Loading...
Wireless Bluetooth Mouse for Apple iPad iPhone MacBook Android Samsung Tablet Phone Dual-Mode Rechargeable 2.4G Portable Computer Mice for Windows Laptop Notebook PC Mac Desktop USB Receiver (Black)
(1,684)
$15.99
FREE delivery Fri, Jun 6 on your first order
50+ bought in past month
Loading...
UGREEN Tablet Holder Stand, 360° Rotating Stand Aluminum Desktop Stand, Multi-Angle iPad Stand Base Sturdy Stand Holder Compatible with iPad Pro Air Mini 13 12.9 11 Inch(Gray)
(289)
$20.87
FREE delivery Fri, Jun 6 on your first order
50+ bought in past month
Loading...
UGREEN Tablet Stand Holder Adjustable Protable Desktop Holder Dock Compatible for iPad 10.2 iPad Pro 11 Inch iPad 9.7 iPad Mini 5 4 3 2 iPad Air Nintendo Switch iPhone 13 12 Pro Max 11 XS XR Black
(49,833)
$14.39
FREE delivery Fri, Jun 6 on your first order
300+ bought in past month
Loading...
UGREEN Mini HDMI Adapter to HDMI Female Cable Adapter 4K Compatible for Raspberry Pi Zero W, 2 W, DSLR Camera, Camcorder, Graphics Video Card, Laptop, Pico Projector, Tablet, 8 Inch
(11,602)
$13.99
FREE delivery Fri, Jun 6 on your first order
100+ bought in past month
Loading...
Introduction to Federal Income Taxation in Canada 42nd Edition (2021-2022) with Study Guide
(17)
$35.99$25.49
PrimeFREE delivery Fri, Jun 6
Loading...
Introduction to Federal Income Taxation in Canada, 44th Edition (2023-2024) with Study Guide
(7)
$89.00$69.00
PrimeFREE delivery Fri, Jun 6
Loading...
Study Guide to Technical Analysis of the Financial Markets: A Comprehensive Guide to Trading Methods and Applications
(868)
$48.04$33.40
PrimeFREE delivery Wed, Jun 4