Question

In triunghiul dreptunghic ABC, masura unghiului A= 90 de grade, cunoastem AB=5 cm si Ac=12 cm.
Calculati : sin B, sin C, cos B, tg C.
Aratati ca $sin^{2}$ B + $cos^{2}$ B = 1

Answer 1

Aflam ipotenuza
BC²=AB²+AC²=5²+12²=25+144=169
BC=√169=13
sin B=cat op\ip=AC\BC=5\13
sin C=AB\BC=12\13
cosB=cat al\ip=AB\BC=12\13
tg C=cat op\cat al=AB\AC=5\12
sin²B+cos²B=1
(5\13)²+(12\13)²=25\169+144\169=169\169=1

Answer 2

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